The rules that I follow for preparing pans for use in baking are:

butter-based cookies: It is recommended that you do not spray or use waxed or parchment paper. But, I usually just spray the pan, anyway.

delicate cookies: I use waxed paper, parchment paper or silpat liners

loaf pan recipes: I usually spray the pan, then place a piece of waxed or parchment paper on the bottom, and then spray it, again. Or, you can just spray the pan on the inside thoroughly.

cake recipes: see loaf pan recipes.

If a recipe has a lot of butter or fat in it, the cake or cookie will not stick as easily. The less fat, the more the baked good sticks. (By the way, it's ok to still use your pans even with residue!)

I hope this helps.