* Don't ride with headphones, hearing is important for your safety.
* Buy lights if you ride at night, it's the law in most places.
* Adults cannot ride on the sidewalk in most places.
* Riding in the street is safer than riding on the sidewalk, because turning cars will not fail to see you.
* Ride further out into the lane when the shoulders are poor. The cars won't hit you and you don't have to ride slow. You're worrying about nothing.
* Follow the laws of the road.
* Keep the tires you have and replace them with slicks when they wear out.
* Unweigh your saddle when you hit bad road. Keeps your knees and elbows bent so they can absorb the bumps.
* Road bikes with skinny tires don't work very well in rough conditions. There isn't much a rider can do apart from the point above.
Read this page. It will teach you important traffic riding skills:
http://bicyclesafe.com/