I try to go easy on those, as I vaguely recall reading that frequently taking melatonin for long periods of time can have some unpleasant effects, but yeah, I finally picked some up, and I've used them on rare occasions when I absolutely cannot get to sleep or when my sleep cycle is way out of whack, and they definitely do have an impact.

I try to keep the room dark. Don't drink caffine near bedtime. I have one of those blackout masks to really get rid of any light if necessary. Avoid thinking about anything interesting or with emotional impact. Get some exercise prior to going to sleep. I've rarely had problems with sounds keeping me awake, but I have some silicone ear plugs for the very rare times that that comes up.