C25K is supposed to be a great starter's program. I have many friends who have had success with it.

I actually started running as a way to get exercise and explore the new town I had moved to. At some point I started really enjoying it - now I've done 3 marathons and am running ~50 miles/week. (And have a 10-mile race tomorrow!)

I guess if I had to share the most important advice I could think of it would be: run slowly. Don't run as fast as you can except when you race or when you do speedwork (which a beginner shouldn't even be considering).