Here around Seattle we usually pay for it by getting parking passes for the trailheads. You pretty much have it right; you can just hike off the trail a bit and pitch a tent. I think it's best to be out of sight of the trail, and in case it gets foggy I like to take a compass reading so I know which way the trail is in the morning.

I knew a mountaineer who liked to hike a few days away from the nearest trail so she could get away from it all, but to do that you need to be comfortable using a map & compass.

Other than that, pack out what you pack in, don't feed the animals, try not to disturb the vegetation too much, and follow any regulations about food storage and fire use. Good luck. <img src="/forums/images/graemlins/grin.gif" alt="" />