I don't know if it works, but you could try counting sheep. Imagine sheep jumping across a fence and into a barn, and continue to count. It is childish, but in most cases it helps me.
Man I stopped taking pre workout and started pure creatine instead.. Not taking all those stimulants makes a hugeeeee difference I sleep a lot better for the most part. Plus I actually have dreams now instead of laying in a semi sleep/ awake state
What I do is I plugin my headphones at night and try not to think about anything just listening to the song and I just daze off and crash instantly, you should try it. Avoid using your phone or the computer or else you'll end up staying awake longer than you think.
Make a solid intention, "I'm going to sleep now." Just relax, try not to think about anything, and you'll start to doze off hopefully. Also, reading say a book or something is a quick way to engage yourself and then sleep, because of the simplicity and calmness.