Honestly, the best way is to befriend hunters ... people who have been hunting for a while. That's by far the easiest and fastest way to learn. Other than that, Google earth. It can be terribly deceiving though. So don't be surprised if you show up and the terrain is nowhere near as open or easy to hike through as it looked on your computer screen.
Having said that it's still a great tool to tell you that you're not wasting your time hiking an hour through some thick stuff only to come out onto a road you could've just driven up yourself.
There's really no magic formula. It kind of depends on what you like. I prefer to just look for spots that don't have a lot of roads through them, that look somewhat open, and then just go and take a look or go for a hike. Sometimes it works. Sometimes it ends up a bust.