Many have popularized the cadence of 180 steps per minute as the goal to shoot for. But there's nothing inherently "magic" or beneficial about this cadence. There's going to be variation among individuals, depending on how fast you're running.
The next time you go running, count how many steps you take in one minute. If you're under 170, then you should focus on improving that number by about five percent. New runners tend to have a step rate of 165 or lower, so it's a good opportunity to increase your cadence (while running the same pace).
Land Underneath Your Body
Foot strike is far less important than where your foot lands in relation to the rest of your body. In trying to run faster, many runners try to "reach out" with their foot to cover more ground.
This promotes overstriding and an aggressive heel strike that sends a significant amount of impact stresses through your legs and can increase your risk of a running injury.
Instead, it's more beneficial to focus on landing directly underneath your center of mass. When landing under your hips (which is much easier if you have a cadence over 170 steps per minute), you'll distribute impact forces more appropriately.
This compact style of running promotes a more neutral foot strike. Just like you don't want to slam down on your heels, you also don't want to land aggressively on your forefoot. A midfoot—or even mild heel strike—is preferred.
A helpful cue to make this easier is to try to land behind your body. While it's impossible to actually land with your foot behind your center of mass, this cue promotes a more efficient stride with your foot landing where it should—underneath your hips.
Stop focusing so much on your heel strike (or midfoot or forefoot landing) when there are far more important elements of running form to consider.
When you get these elements of form right, you'll become a dramatically more efficient runner. And that means you'll race faster.race.