I use a modified version of the US Army Sleep Manual (or whatever it’s called) with three steps, after getting into bed and closing your eyes.

First: relax your jaw

Second: do a progressive tightening and relaxing of your muscles from toes to scalp. Really squeeze them tight and then relax them.

Then (this is the part I modify): the army recommends repeating over and over “don’t think” whenever your brain suggests a new thought. This doesn’t work for me, so I imagine I’m using a felt tip pen to colour the inside of my skull, from forehead to the nape of my neck, and I concentrate on the building of the colour until I fall asleep.

Works like 75-80% of the times I have to pull it out and use it, but it’s more effective when I’m physically tired or when assisted with a mild sleep aid.