A brain-dump:

• Have a bed-time ritual like changing into sleeping clothes, meditation, writing in a diary, ... anything that is more complicated than "Oh it's 3 and I have to be up at 7"
• Eat something sweet a quarter or half hour before lying down. This seems to help people. Of course, don't gorge on that.
• Speaking of food, people are advised not to eat too much before bed. I don't have that problem aside from usual overfeeding and associated discomfort, so YMMV.
• If you have trouble with sleeping through the night or falling asleep, Melatonin can help. Recommended doses vary widely, 1mg should do the trick.
• People report falling asleep better on days they've exercised. Strength training seems to be more helpful than endurance.
• Generally fixing whatever bothers you while falling asleep helps. Too loud? Fix any noise sources, wear ear plugs. Too bright? Cover any light sources, shut the blinds, wear a sleep mask.
• Have a set schedule. Apparently a set waking time is more important than a set time to sleep. Personally I find it only helps if you are really strict with your schedule and do not party as young people tend to do.
• Apparently blue and blue-ish light in the evening disrupts sleep. Try installing f.lux or redshift if you absolutely have to look at a screen, else try to avoid screens altogether.

The general problem is that "having issues with sleeping" in any way (too much, too little, difficulty falling asleep, difficulty waking up, difficulty sleeping through, drowsiness, nightmares, restless leg syndrome, sleep walking, ...) belong to the category of symptoms "well this happens when you have any kind of problem" like headaches, lack of motivation, discomfort, feeling a little sick. If you have tried a number of the things listed above with no success consider seeing a medical professional to rule out an underlying medical issue.