Now you know you like baking and want to get into it a bit more. If you feel a bit lost, go to part 1.
Ingredients
Whatever you use frequently, or whatever keeps you baking from what you want to bake. The list below is what I frequently bake with.
Cocoa and semi-sweet or bittersweet chocolate
Two things: chocolate cake and hot cocoa. Need I say more? Probably not, but I will! Most recipes call for semi-sweet or bittersweet chocolate, not unsweetened. There is a legal definition for a minimum chocolate content for each. At this point, anything over 50% chocolate is probably overkill, and, if the recipe is just a little liquid, can cause the chocolate to seize. Cocoa butter is a crystal, and, with too little liquid, the crystals won't melt properly. Natural (not dutched) cocoa is most used in America. To measure, place the measuring cup onto a piece of clean wax paper; spoon into the cup and level; pour the excess back into the cocoa box.
Brown sugar
Light or dark. Most recipes specify light; I prefer dark for the stronger molasses flavor. Measure by firmly packing into the cup and leveling off. Break up the clump of measured brown sugar with a whisk or sieve.
Baking soda
It's not just for your teeth! It's also a great cleanser, and a leavener. Well, half a leavener, it needs an acid to react with to release carbon dioxide. It's used when an ingredient in the recipe is acidic, like natural cocoa, lime juice, pumpkin and buttermilk. One-quarter (1/4) teaspoon is enough to leaven a cup of flour. Like baking powder, the leavening reaction produces salt along with the carbon dioxide.
Lemon, orange and almond extract
Perhaps this is just a Christmas cookie thing, but it seems that anything that doesn't call for vanilla or cinnamon is lemon, orange or nut-flavored (spritz, lemon-poppy-seed muffins). Although I use zest more than extract (I freeze the lemon juice for later), lemon and orange extracts have the advantage of lasting nearly forever and taking up much less space. One-half teaspoon of extract substitutes nicely for the zest of one lemon or half an orange. Almond extract can give an extra punch to real almonds when used sparingly.
Cloves, allspice and nutmeg
Fall and winter baking frequently include other warm spices along with the cinnamon, most often cloves, allspice and nutmeg. My own favorite is nutmeg. The advantage of using individual spices is adjusting the ratios to your own taste, or even use them without the cinnamon.
Shortening
Pros: shortening last forever. Cons: used only in pie crust and American decorator icing, perhaps in deep frying (does anyone else remember those commercials with the family emergency that interrupted the fried chicken?). If you make pie crust, you've probably got a can in your fridge already.
Yeast
If you are a regular yeast bread baker, you don't need me telling you to keep a few packets of yeast in the fridge. If you aren't, and would like to be, stock up and check out Artisinal Bread in Thirty Minutes.
Equipment
When you know you like to bake and you've got some skills, then it's time to buy those "basic" tools: a better mixer, other sizes of spatula/scrapers, a balloon whisk and a small whisk, a zester, good knives, a sieve, a reamer, parchment paper, extras of the tools used most often.
Extras, extras, extras
Personally, I find a second (and third, and fourth) set of measuring cups and spoons very handy, along with extra bowls and spatulas (see below for that). When baking more than one recipe at a time (say, Christmas cookies), it's much easier to grab a clean measuring teaspoon or mixing bowl instead of running to the sink to wash something off. Secondly, if you worry about cross-contamination of allergens — and everything is an allergen — you'll often use three half-teaspoon measures in one recipe. Anything you find yourself washing mid-baking is worthwhile to have a spare of.
Parchment paper
Parchment paper is so darn useful it should almost go into the basic tool section. Not even meringues will stick to it. It's paper and can be trimmed to fit any flat-bottomed pan. It stands up to multiple bakings and can be re-used for sheet after sheet of cookies.
Whisks
Not just for whipping cream and egg whites, whisks are the best tool for thoroughly mixing ingredients, either thinner batters or even dry ingredients to eliminate clumps of baking powder, cocoa or brown sugar. Whisks are even useful in cooking, for salad dressings and sauces.
Sieve
Older recipes say to sift flour with other ingredients to combine them, but whisking is better at combining. Sieves, on the other hand, are also good at getting the lumps out of cocoa and brown sugar, and draining pasta.
Zester and reamer
While a fork can juice one lemon or lime effectively, a reamer or juicer is more efficient. Plastic is the least effective material for a reamer. My grandmother's glass reamer still has a nice edge on the ridges that does a good job of scraping and bursting the pulp. The Amco brand citrus presses are supposed to be very quick and extract a lot of juice; a cocktail expert friend uses one for his parties. If you prefer lemon or orange zest to extract, you'll also want a zester that can finely shave citrus peel. As cliched as it is, the Microplane works very, very well and makes fine zest. Other zesters are designed to make a longer, thicker zest. They take a lot of hand strength and time. And don't confuse that with the part used to cut a "twist" of peel for a cocktail. Mmmmmm. Cocktails.
Good knives
Even baking requires knife work; make your life easier and buy good knives. For price to performance oomph, check out Victorinox's plastic handled knives; they had a good review in Cook's Illustrated and I've been using them for decades. While baking I use: a fourteen-inch serrated knife to "torte" cakes, that is, cut a cake into layers; a ten-inch wide-serrated blade to slice breads and cakes; and a chef's knife to chop ingredients and halve citrus for juicing.
Spatulas
Now is the time to expand your spatula collection beyond the all-purpose medium size. As much as possible, stick with silicon blades and handles that can go through the dishwasher. Get a smaller size for getting into jars (get that last sticky bit into that one-quarter cup measure), a larger "spoonula" for scraping out large blobs of whipped cream or egg whites, and a Viennese spatula for folding (see below) and frosting.
Pastry cutter
If you make pie crust, scones, biscuits or anything with butter "cut in" to flour, the easiest way is with the pastry cutter. I like the wire kind, because it gets into the corners better.
Rolling pin
Either a French rolling pin without handles, or a large-diameter pin that will keep your knuckles from dragging in the dough. Wooden, because at a large enough diameter, marble will be insanely heavy.
Skills
Whip cream and whites
A cup of heavy (or whipping) cream or one or two egg whites can be whipped by hand with a little effort, but more than that and I need a mixer.
For the cream: Use a balloon whisk (large, many tines) and three- or four-quart bowl with straight sides to minimize splattering. If the day is warm (or, more specifically, the kitchen is warm), do pop the bowl and whisk into the freezer for five or ten minutes. Pour about a cup of heavy or whipping cream into the bowl. Add a tablespoon or two of sugar and a teaspoon of vanilla extract if you want. Tilt the bowl to a 45-degree angle, or steeper, so that you can hold the whisk nearly horizontal. Now, whip. Start slowly and controlled, working up speed, using your forearm and wrist. Cream should not take more than a minute or two, but it will feel longer. When my forearm wants to fall off, I will hold the whisk loosely and whirl it around the bowl. Whipped cream goes quickly from soft peaks to overwhipped to butter.
For the egg whites: Whipping whites uses the same technique, although it takes longer. As I said, I can whip at most two whites, and then only to soft peaks, and never with sugar. (What's this soft peak that everyone talks about? Pull the whisk or beater out of the eggs or cream; if it makes a curlicue, that's a soft peak.) For whites, an egg beater or mixer makes the job much easier.
Again, if the kitchen is warm, chill the bowl and whisk/beaters before starting. A copper bowl or pinch of cream of tartar helps the whites maintain their lift after baking, but aren't necessary. Start slowly, and speed up once the bubbles become smaller. After whipping many, many egg whites, you can almost tell from looking at them if they are soft or stiff peaks. Until then, check often by pulling the beaters out of the whipped whites. A curlicue means soft peaks. Stiff peaks will stand straight up, looking like a mountain top. Then there is dry, when the whites start to look lumpy, and will be a right bugger to fold into the batter.
To make meringue, whip the whites to soft peaks. Then add one tablespoon of sugar and beat again to soft peaks. Add another tablespoon of sugar and beat. Adding sugar to whites and keeping the whites from deflating requires patience and much beating.
Fold
Folding is a way of carefully mixing in one ingredient like whipped whites or whipped cream into a batter, without the first ingredient losing all the air you've beaten in to it. Some recipes, like Springerle, reverse the process by folding the flour into the whipped egg-sugar mixture.
Traditionally, folding starts with scooping one-third of the whipped ingredient onto the batter it's to be folded into. Take a spatula (Viennese spatulas work particularly well), cut into the middle of the ingredients down to the bottom of the bowl. Twist the bottom of the spatula towards you and scrape it along the bottom of the bowl. When the spatula hits the side of the bowl, turn the bottom of the spatula up (the spatula has flipped), and scrape gently up the side of the bowl. At the top of the batter, turn the top edge of the spatula towards the center of the bowl and give the bowl a quarter turn (less for enormous bowls). At this point, the spatula has done a complete flip and is back at the center of the bowl, ready to cut in again. The motion has pulled some of the batter over the whipped whits or cream. Repeat until most of the ingredient has been worked in.
Add the remaining two-thirds of whipped whites or cream, and fold in until completely incorporated. Don't rush. With practice, you'll become faster.
Cutting butter
Cutting butter (for pie crust, biscuits, scones) requires either a pastry cutter (also called a pastry blender) or a food processor. The food processor is easier. The cutter is cheaper and easier to store. I prefer cutters with wire tines, but most sold today have solid metal sides with four or five tines coming off that.
The butter should be straight from the refrigerator, but not frozen. With a knife, cut the butter into tablespoon-sized pieces; cut those pieces in halves or quarters. Toss the butter pieces with the flour, so that the flour completely coats the butter. Wielding the pastry cutter/blender, cut through the biggest butter pieces. Turn the bowl a bit, and cut through the next biggest butter pieces. Use the pastry blender the mix the butter and flour up again. Keep turning, cutting and mixing, until you notice large chunks of butter stuck in the cutter. Pick them out with the knife back into the bowl, and mix into the flour, then keep cutting.
Keep cutting until the pieces are the size called for in the recipe, usually the size of peas, although I like mine a bit smaller. Continue with the recipe as directed.
To use the food processor, cut the butter into tablespoon-sized pieces, and add to the flour already in the processor bowl fitted with the chopping blade. Pulse in two second bursts until the butter is still a bit larger than the recipe specifies. Add the liquid ingredients and pulse to combine; this will further chop the butter.
Books
Now we get into the chemistry of baking, the why of it working. Oh yes, baking is chemistry, even more so than cooking. Yes, you can be an excellent baker without understanding the minutiae behind how it works, but it's just so nifty to know why something works.
Bakewise
Shirley Corriher wrote what could be a textbook for a beginning food chemistry course. Corriher starts with how ingredients react with each other, and illustrates each concept with recipes that take advantage of those reactions. It's helped me to read a recipe and realize why it wouldn't work, and how I could make it work. It also helped me to realize why my buttermilk biscuits tasted of soap (once the baking soda is included for the buttermilk, there is twice as much leavening as needed).
The Ratio
Michael Ruhlman has a mission to free bakers and cooks from doggedly following recipes without knowing what can be changed and what can't. Half the ratios are baking, and half are for cooking, like making emulsions and stock. Ratios might seem modern, but to my mind they are quite old fashioned; we all have an image of the grandmother who cooked and baked by handfuls and pinches. She knew her ratios so well she needed no scale or measuring cup.
Ratios have saved my Stollen. It was realizing the liquid to flour ratio for the original almond stollen recipe was far out of whack that enabled me to bake an edible loaf. The book has also rescued my stock: less water, more vegetables. Who knew it could be so simple? And Ruhlman's goal is to make recipes so simple to understand that more people to whip up a their own dressing or bread.
One caveat I have for Rhulman's book is that he forgets that not everyone has the time to whip up a batch of stock after roasting a chicken. In other words, not everyone is a freelancer working at home. Some of us finish dinner, bathe the kids, and collapse directly into bed ourselves. But, if you can ignore the occasional blind spot for time, it's an excellent book.
The Cake Bible
Rose Levy Berenbaum's book appears on everyone's list of baking books, and for good reason: the results are professional level, but the instructions are detailed and direct enough for the passionate amateur. She's also written a comprehensive reference when you need to know how much cake for how many people, and especially how much icing for that much cake.
Recipes run from the easy (butter cakes, pound cakes) to the architectural (wedding cakes, buche de noel, the enchanted forest cake). Often, what looks particularly difficult is much easier in practice (like the mousseline buttercream, made with sugar syrup.).
I particularly like that measurements are given by volume, American weights, and metric weights.