I'm no expert, either, but I have heard that you should aim for 85-95 footstrikes (per foot) per minute. So, in other words, your right foot should hit the ground 85-95 times per minute as well as your left. This may feel like way too many at first, but trust me, once you get used to it, your feet and legs will thank you. Aiming for this many footstrikes per minute will force you to shorten up your stride, which is also a good thing. Many experts will tell you that you should try to avoid "bouncing" as well, meaning that if you pick a spot on the horizon and stare at it, your head should not be bobbing up and down too much as you concentrate on that spot. Try to keep your torso as stationary and upright as possible and let your legs do the work instead. They will also tell you that if you try to propel yourself forward vs up-and-down, it will keep you lower to the ground and cause less impact.
In high school and college, I used to run with a much longer stride, but when I got into real distance running, I learned to shorten (and quicken) my stride and it has improved my form immensely.
Hope this helps!
Steve