Everyone has a different sleeping pattern. In other words everyone has a different bed time routine. Some people sleep before 10pm and some people sleep after 10am. The thing that you should do before you sleep is think positive thoughts. Keep negative thoughts out of your mind. If something is bothering you then I think the best thing to do is to distract yourself with a hobby like read a good book in bed, listen to soft soothing music and write your thoughts in your journal. Read up on wikihow on how to get rid of negative thoughts. They have good tips and I think those tips will help.
Some people are light sleepers, some people are heavy sleepers and some people are in between. For light sleepers, please put on your earplugs as you get to sleep to avoid distractions. The time you wake up in the morning depends on how much you have slept. I think that the best thing to do to get enough sleep is to sleep
between 10pm and 12am and wake up at 10am. If you want to wake up at Fajir time set your alarm clock between 4:30- 6:00am or ask your parents to wake you up so you don't have to do Qadha. If you have an exam coming up I think the best time to study is after lunch or in the weekends. I don't think it is a good idea to cram for an exam the night before the exam because you'll become drowsy in the morning and won't get good marks in your exam.
Avoid eating junk food or anything too heavy before sleep so you won't get any nightmares.