People often ask me what sort of drills should they do to optimize sprint mechanics. Although there are literally TONS of speed drills designed to boost running mechanics - most of them are worthless. I've generally been in the camp that says running is natural and technique is mostly a result of how the body is functioning. In other words, if an athlete is strong/powerful enough in the right muscles and is able to activate the right muscles at the right time (has enough mobility and no movement impairments), his technique (and speed) will be fine.
This is more true than not - athletes that are functioning well and who are strong and powerful in the right places will inherently run fast with good technique.
Running fast is really quite simple: The more force you get into the ground, the faster you go.
Having said that, there are a small handful of drills that allow you to setup in a way that will enable you to efficiently get more force into the ground. The simple "stepping over" cue espoused by the great Charlie Francis via Gerard Mach is one such cue. It's very simple, but doesn't always come 100% natural. I have seen it's implementation quickly knock tenths off sprint times when implemented with some technique naivete athletes. To learn more about that watch this video by Latif Thomas:
Here is a simple progression to follow. Start with A-march, then progress to A-skip and A-run.
I recommend 2-3 sets of 25 yds each after a general warmup and as part of your speed work.
I also highly recommend Latifs complete speed training 2. It's a great resource for the speed seeking athlete or coach: