Ways to get better sleep?

I have always had trouble sleeping. Usually I end up taking some Benadryl to sleep plus other personal reasons. I also drink a sleepy time extra tea that is amazing at getting me tired and relax but doesn't help me sleep really. I listen to sleepy meditations too. Like rainstorms or even guided ones. I am getting ready to apply for college again and will need the sleep. I need ideas. Also yes I have talked to my doctor about this many times. We have tried many different pills. One put me in the er when I was in middle school. One made me so grouchy I would just snap and it hard to stay awake. Several just didn't even put me to sleep.

What can I do?