First tip (and I will admit I don't know how relevant it is) do NOT nap during the day.
Second tip, exhaust yourself during the day. Keep busy. Go for a run if need be.
Lastly, after exhausting yourself and not napping, go to bed at your desired time. If you have trouble drifting off and have a smart phone, get yourself the lightning bug app. It plays rain type noises to give you something other than your thoughts to focus on to get to sleep. (I used to take up to an hour to get to sleep, with lightning bug I am always asleep within half an hour)
Good luck
'People are never perfect but love can be. People waste time looking for the perfect lover rather than creating the perfect love' - Princess Leigh-Cheri from Still Life With Woodpecker.