Removing all distractions, which takes a bit of work. Covering every single source of light. Little indicator on my charger? Slapped electrical tape on it. Blackout curtains. Noise machine. The hardest one: Never using the bedroom for anything but sleeping. Not even a little peek at the phone and YouTube for a relaxing video. I have an analogue non-illuminated clock for daytime, and if I need to check the time in the dark, a Timex I can hit the glow button on. If I really can’t sleep, I get up and go into another room to read or listen to something.