Alcohol is a stimulant in small amounts. Not so good for sleeping. Stay away from ALL forms of caffeine after 1 or 2 PM, including coffee(even decaf),cola, tea (unless caffeine-free herbal tea), chocolate (a biggie), and items that might have these ingredients even in small amounts. Some people are mnore sensitive than others. Eat a fleishig meal containing a tryptophan-laden ingredient (like turkey), or a milchig meal, but not too spicy.
Don’t watch TV or go on your computer within a couple of hours of bedtime. Read something. Even though you may not realize it, the mind being stimulated by TV or computer can find it hard to wind down. Listen to quiet, gentle music if you can.
I personally find the use of a fan, blocks out extraneous noises, and is cheaper than a sound machine. But, be careful, it is habit-forming and you can become dependent on it in order to fall asleep.
If you are milchig and all else fails, warm milk works wonders.