Some people just have trouble sleeping! However, there are some things you can do. The idea is to train your body and brain. Humans are creatures of habit! The following is a list of good sleep habits:
1. go to bed at the same time every night and get up at the same time every morning.
2. sleep in the same bed every night .
3. use your bed for sleeping not reading, watching TV, computers, etc.
4. keep your bedroom temp. consistent, comfortable.
4.5. a darkened room is also helpful
5. some exercise everyday ( but not right before going to bed as that may stimulate you).
6. no large meals right before bed time (a small snack is ok if really needed, maybe milk, bananas, etc)
7. no caffeine after 3-4:00 pm (some say after noon, some say after 6:00 pm)
8. take clocks out of the room (clock watching is frustrating and anger will keep you awake: if an alarm clock is necessary then set it and turn it to face away from you)
8. schedule some "worry time". About 1/2-1 hour, before bedtime, review you past day and what you expect tomorrow. Cover everything. If there is something you forgot to do then do it now. Plan out solutions to problems that can't be dealt with now. When you go to bed and these worries crop up just remind yourself " I've done all that I can do and the rest I'll do later. I've already worried about these things and I WILL NOT worry anymore now".
I'm sure there are other things one can do and I'll post them as I remember them. Remember, The idea is to build consistent, good, sleep habits. You want your body and brain to automatically relax and go to sleep.