idk if any of these will work for you bc tbh, i'm a bit blesssed in the sleep dpt. i usually dont have problems but here's some things i'll do if i am not drifting quickly.
The "Full Body" - start at your toes and completely relax them. Work your way up from toes to the tip of your head (I never make it all the way). You have to really be mindful about whether or not each body part is truly and fully relaxed.
The "Just Rest" - don't put any pressure on yourself to fall asleep. Remind yourself that even laying there, eyes closed, is rest and is good for your body.
The Day Dream - my usual method. Start to imagine a fun scenario. I mean really get into it and the details. I usually end up transitioning into a dream from here.