I'm not that experienced, but I read Runner's world a lot ;-)
Mostly, I think you want to run the way that feels natural to you. Try to go outside and run as fast as you can for a few seconds. Chances are that you land on the ball of your foot, but you can't run like that for long. Then try to run slowly for a mile or two. Chances are that you land on your heel and run forward to your toes to kick off. That's the way most people run, and I feel that you shouldn't try to change it too much. Most people have some defect somewhere in their body, and the body finds the best way to run to work around those defects.
However, not everybody agrees with that. Dr. Romanov believes that landing on the forefoot no matter how fast or slow you run will prevent injuries. It's called the Pose method, and you can read about it here:
http://www.posetech.com/pose_method/technique.html. I think that's for advanced runners, and for me who wants to run for fun and endurance it's not a good idea to change my natural way of running too much. You will just have to do some research and find what works for you. There are lots of running sites out there!
