Avoid stimulation immediately prior to sleep e.g. screens, intense exercise, arguments.
Make the bedroom a place of rest exclusively, no screens, noise, etc.
If sleep is elusive don't stay in bed, go do something and come back later to try again.
Worrying about sleep only makes sleep more difficult.
Don't use alcohol or drugs to help sleep except very briefly to get over a hump. Of the benzodiazepine class, zopiclone is effective for short periods to re-establish a sleep pattern.
On the worrying point. If you find yourself worrying that you can't fall asleep, remind yourself that just laying there is giving yourself a chance to slowdown and relax. Giving yourself permission to relax is the first step to letting go of the worry.