The biggest thing to learn beforehand is the habits, preferences, and tendencies of the animals you want to trap.

But why are you bothering with snares? I you're in the country already, you could lay in a store of proper quick-kill traps and start working with them.

For that matter, you could lay in some live-catch traps. If you develop techniques that work with those, you'll be well prepared for tougher times.

(Hmm, and if you could live trap hares, a buck and a couple of does, that's possibly an endless protein supply ...)