This may sound obvious given sleep is a relaxed state but relaxing before sleeping is crucial.
Ways to do this include having a warm bath, writing to do lists for the next day, relaxation exercises or yoga, listening to audio designed to help people fall asleep and reading a book are all ways recommended to help you relax before bed.
So too is avoiding looking your phone, tablet, or laptop.
Looking at these devices an hour before trying to sleep can have a negative effect; this is due to the light emitting from the screen rather than what a person is reading on it.