Lots of great tips here but what I find the most important is feeling tranquil / mentally relaxed when I go to bed. Your body might be tired after a long day but if you're suffering from chronic stress/worries then those feelings will hinder you from finding the tranquility required for a good night's sleep, as your mind keeps wandering. Try resolving the issues that cause you these worries but at the same time try cultivating mindfulness through meditation and introspection. You mentioned you can't meditate but that's a beginner's problem that resolves itself with time. Look up the lectures of Jon Kabat-Zinn on YouTube or pick up a book of his. He does a great job of teaching mindfulness as a tool for resolving stress and worry and he's one of the pioneers in the scientific study and development of mindfulness practices. Good luck and lots of love to you, comrade.