It's a big sky, but I find the following techniques help make things a bit more relaxing:
1. (As already mentioned) choose slightly odd cruising altitudes. Most people use thousands or thousands + 500 ft.
2. If you use a VOR as a turning point, "cut the corner" a bit - don't fly right over the beacon.
3. In summer, if you can fly above the cloudbase you will avoid the gliders. If you can't then try to avoid flying under growing or developed cumulus clouds.
4. There will be more gliders upwind from a gliding site than downwind. (Same goes for parachutists!)
5. In the circuit fly at the correct altitude, fly the circuit pattern that people expect you to use and try to make radio calls in the right place. (At the field where I trained, there was a collision in the circuit between a Rallye which was flying a normal circuit, and a C172 which flew a tight circuit without making any radio calls. The Rallye descended onto the Cessna on finals. )
6. Descend into airspace that you can see. I scared myself badly one time by doing a long straight descent on a reciprocal heading to a flexwing microlight who was doint a long straight climb....
7. Don't rely on the other guy to obey the rules of the air!
8. If you're flying a C150, fit a rear-view mirror!
