Originally posted by wanderfast:
How is the best way to prepare plywood so it will not warp or be otherwise undesireable?
For what? A painting support? Drop that question into the Oil Painting section and you will get 30 different answers -nearly all of them correct!
Easiest way is to brace the back with 1"x2" glued on with construction adhesive. Sand, seal with PVA, Acrylic medium, etc., then do it over again three or four times. Prime it with either acrylic gesso, oil canvas primer, or glue-chalk gesso. Sand, prime, sand, prime sand. (I forgo the sanding, but I like the texture).
But the Oil Painting section people will have more theories, opinions, and methods for you.