I'm not an expert on sleep hygiene but I do know of one system. You decide the average number of hours of sleep you are getting per day, then you block out a time of that number of hours. So let's say you are getting 6 hours of sleep - 3 at night and 3 in the afternoon. You block out a six hour stretch, say from midnight to 6 am, and you only stay in bed for that period. It's very difficult, but you don't sleep at any other time. Eventually your body will learn to stay asleep for six hours during that period. Then you extend it to seven hours and so forth like that. They call this sleep consolidation.

The usual stuff... no caffeine, no other stimulants.

Avoid looking at a computer screen late at night.. the light will tell your brain it's daytime. I have a hard time avoiding computers entirely so I use blue-blocker sunglasses while I work on the computer for the last few hours before bed.

That's all I know about but there is a great deal more information on sleep hygiene.