stretching is very important. Don't slack on it. You need a good 5-10min of stretching after every run. If you don't, you're in for a world of hurt.
I had IT band problems because I wasn't stretching enough when I started training for triathlons a few years back. Painful to just sit in a chain. Took 3 months for them to calm down enough so that I could train. I stretch a lot now.
I'll second the good shoes. Go to a running store, not some store in the mall. Find a good pair of shoes. They'll be expensive, but will save you from injury.
Work on your running form. Little things, like landing on the balls of your feet, foot striking the ground underneath you instead of in front of you, rotating your pelvis forward a little (push your crotch forward)... all the little things that add up, especially when you start adding mileage.
And stretch. A lot.
"There isn't any secret," he said. "It's all very obvious."