First and foremost, go to your nearest BLM office. There is one in almost every town out west. They have maps. Some Forest Service offices also have BLM maps, but I go to both and get all the maps they have. The advantage to going into the office is then you can ask about local closures (fire season) and areas commonly used for shooting. If you go to an area that is not commonly used, PLEASE pick up your crap and as much of your brass as possible. No broken bottles, and left-over targets. I shouldn't have to say that, but still...