Things that have helped me:
Having a regular wake-up/get up time and stick to it everyday (with the ocassional exception for social life disrupting it).
Having a regular bed time and sticking to it.
If I'm having trouble getting to sleep and have been lying in bed awake for more than 15 minutes, then I get out of bed and do a quiet, non-stimulating activity, like reading a book. I keep the lights dim so I don't confuse my body clock that it’s time to wake up. Also I stay awayd screens of any kind—computers, TV, cell phones, iPads—as the type of light they emit is stimulating to the brain.
How to Sleep Better: Tips for Getting a Good Night’s Sleep <- for some other tips and help