Here is a good article to read if you are just starting out (btw, Hal Higdon is a writer for Runner's World, so this is typically the kind of stuff you see in that magazine, including nutrition suggestions, etc.)

http://www.halhigdon.com/beginrunner/intro.htm

Things important there? Run defensively, try to run with a buddy if you can, run on the shoulder FACING traffic so you can see the cars coming, and just be alert...there are idiot drivers out there. I also wear one of these just in case something were to happen:

http://www.roadid.com/id.asp

Hope this helps.