Watch your speed. For the most part, you can get away with being over the limit, but you never know when some hard case of a patrol officer is lurking just beyond the next billboard. Being more than 20 mph over the limit is usually (depending on the state) a more serious offense than being 1-20 over.
If you get stopped, be polite to the police. Traffic stops are one of the more dangerous parts of their job, so they might be a little on edge. Call the officer "Sir" or "Ma'am" (whichever is appropriate). Keep your hands visible, and before you do anything (like, say, going into your pocket for your license), tell the officer what you plan to do. Do not admit to anything illegal. Whatever you say is admissible in court, so if the officer asks you if you know how fast you were going, do not admit to having been over the limit. You can say something non-committal, or you can say nothing at all. Signing and accepting a ticket is not an admission of guilt.
Stay in the right-hand lane, except to pass. In most states, a solid yellow line in the middle of the road means that passing is illegal. If one line is broken, passing is permitted on that side of the road.
If you see a sign that says, "Last gas for X miles," take it seriously. Likewise for signs that say "Private property" and "No Tresspassing".
Chain restaurants offer consistent food, but you're more likely to get a truly memorable meal at a mom-and-pop place.
Don't be afraid to talk to people.
Take lots of pictures and post them here.
Have fun.
