Proper form for running --- Roll off the ball of your foot, smoothly , not bouncing up and down, keeping your head as level as possible. --- practice your form --- than pick up the pace keeping your form. --- Minimize jarring impact with each stride. If your running flat out it will take some effort to develop a low impact comfortable stride.
One thing I neglected to mention, R: Try to run on dirt, grass or a track; concrete or pavement will eventually take a terrible on your legs, especially your knees. It's understandable to want to run on pavement, especially if you live in the city. It's flat, and you're not surprised by a hole or something that might turn your ankle. But if you can possibly find another surface, do it. It'll allow you to run pain free many years longer.