Well, actually there's probably only 2 or three rules per say. The first is homemade crust may be better, but those crusts from the refrigerated section are so much easier.
2. Fresh fruit fillings aren't that difficult so avoid
canned. Also, what's up with weird fillings like crackers to make mock apple pie.... No . It's a cracker pie. But if you're not in California like me and can't find anything decent fruit wise at a reasonable price..... Ya know what ? I've had it .... Cracker pie isn't that bad. Just call it what it is. Raisin or funeral pie is pretty good too, but I think the brandy helps. Add a good quarter cup....so the recipe just says use vanilla... Do it....you'll thank me.
There is only one BAD pie as far as I know. My Dad was in the Navy during WW2 and on his ship there was a pie made from canned fruit cocktail that was so bad you hurried through the line with your tray so you didn't get stuck with 2 pieces. Back then you got in trouble if you didn't eat everything on your tray.
3. One pie is good but 2 are better. Obviously.
Okay, there seems to be more than 3 rules.
4. Pies are not dessert only. The prime directive of pie is that it be served at all meals until it's all gone. So, Breakfast pie and coffee is perfectly reasonable.
5. Eating pie directly out of the pan when it's the last piece is okay. When there's still more than one piece? Make sure no one's looking or home. Don't leave any stray whipped cream.
Here's a basic recipe for Funeral pie
http://allrecipes.com/recipe/funeral-pie/
And one for mock apple/ cracker pie
http://allrecipes.com/recipe/mock-apple-pie/
Enjoy your pie.