1. Go to bed & wake up at the same time each day. Even at the weekends. Sleeping late at the weekend makes waking early on Monday morning even more difficult. Set yourself an alarm for bedtime as well as waking up.
2. Avoid caffeine. Remember caffeine is found not only in coffee but certain teas, fizzy soft drinks & choclate and can take upto 8 hours to clear your system.
3. Avoid nicotine. Nicotine is a stimulant and often causes us to sleep only very lightly.
4. Avoid alcohol. Alcohol is a sedative so it might make you feel drowsy but it actually disrupts your circadian rhythm (your internal body clock) and therefore your natural sleep cycle. It robs you of REM sleep, wakes you up during the night for the toilet (it's a diuretic) & often causes you to wake earlier than usual in the morning.
5. Don't take naps after 3:00 pm as it may make it harder for you to fall asleep at night.
6. Don't use devices with blue LED light for a couple of hours before bed. This type of light blocks the rising levels of melatonin in your body. Melatonin is described as "The starting pistol" for sleep to occur. The effect caused by the blockage of melatonin can linger over a few days.
7. Leave time for unwinding & relaxing before bed.
8. Ensure your bedroom is dark & cool. You will sleep better in a cooler room.
9. Get out in the sunlight/daylight for 30 minutes every day as this helps to regulate natural daily sleep patterns.
10. Exercise during the day but not too soon before bedtime.

Tips from Why We Sleep by Matthew Walker.