when i go to sleep i try to picture a simple scene like waves or trees waving. Another thing that can help is a body scan where you go through each part of your body one by one and relax it. Sometimes i feel stressed before bed and my head is buzzing with thoughts. I try and write them down in my diary so that they are out of my head or just think of it like a moment that happened to someone else instead of me.
I have lots of dreams and i often remember them when i wake up. I think that if ur calmer before sleep your dreams are nicer.