“Sometimes people are layered like that. There's something totally different underneath than what's on the surface. But sometimes, there's a third, even deeper level, and that one is the same as the top surface one. Like with pie.” ~Dr. Horrible's Sing Along Blog
The most important thing to remember is that a good pie does not have to be visually perfect (that's the charm of home cooking); it just has to taste good. If you are accustomed to store-bought pies, you will be surprised by your first homemade pie (and probably frustrated and disappointed that your pie doesn't look as pretty as Mrs. Smith's). Store-bought pies are engineered for longevity, appearance, and homogeny - they last a long time, slice into neat wedges, and lack everything that makes a homemade pie truly great. In contrast, homemade pies are full of texture and depth and flavor and aroma - and are messy. [Confession: I’ve never quite mastered the art of making cosmetically perfect pie, but that has never stopped everyone from absolutely inhaling them and begging for more.]
Yes, the process of baking is a complex chemical reaction requiring precision and accuracy. But there is no reason to be intimidated by that. You can modify any recipe, but it is imperative to understand the purpose of each ingredient and how they react and interact before attempting any deviations.
The foundation to a great pie, both literally and figuratively, is the crust. And nothing beats a homemade, flaky crust that perfectly complements the filling. It's not difficult, but it does take precision and practice.
Custard pies are the most difficult. They can be either dairy-based or sugar/syrup-based, and both require delicate handling, as they are prone to certain difficulties that other pies are not - they can crack (if they are over-baked or cooled too quickly), pull away from the crust (if the edges finish cooking before center sets), and "weep” (the liquid is wrung out - again, from over-cooking).
Once you've mastered the art of making a crust, fruit pies are the easiest to prepare. No delicate custards, no temperamental meringues - just gooey fruit filling surrounded by delicious flaky pastry. Fruit fillings are easily substituted or innovated with whatever fruit is in season.
Need some extra help? You can find classes and demonstrations (often free) at some culinary stores, such as Williams-Sonoma or Central Market.
Don't worry if the pie doesn't look perfect. Keep the crust cold, don't overcook it, and it will be fine.