I usually have to quiet my mind before I go to bed at night - that's when the racing thoughts are the worst for me. I like to get myself ready for sleep, then sit in bed with some reading - sometimes something light & fun or AlAnon daily readers. That tends to slow my body down & get comfortable. When I turn my light off, I talk to my HP - thank them for my day & the many blessings in my life, list anything that is bothering me & acknowledge there is nothing I can do about it at this time, therefore turning it over to HP. I then ask for peace in my home & a restorative night's sleep & say the serenity prayer. If my mind is still going, I focus on my breathing and try to keep my focus there (kind of like counting sheep), and say to myself "I breathe in, I breathe out" repeatedly with my breathing.
I'm trying to make sure I turn off my laptop & phone at least an hour before going to bed. I don't get to read every night, but find it helps slow me down whenever I can do it. I've also done the body scan that FireSprite mentioned - I mentally put each body part to sleep.