I first try to just relax, maybe make up a story in my head while I lie in a comfortable position with my eyes closed. If that fails, I try to read or watch something tire me out. And if there just is no sleeping. I get back up for a little while and try again later.
Forcing myself will not work, the act alone will guaranteed keep me up. Now that I'm no longer forced to work early shifts and primarily work nights, I have less issues than I used to. I know that while I might not get the optimal amount of sleep, I'll still get a decent enough amount to function the next day. And not having that stress looming over me anymore helps me cope when I struggle to fall asleep. That at least I no longer have to get up in a few short hours.