I’m sure this is only a me thing, but for me I found it easier to concentrate on specific sounds… Like the ringing in my ears.
As a kid, I’ve always had ear ringing, but it doesn’t bother me too much in day to day life. I do have to ask people to repeat themselves if I’m not focused directly on them or cant read their lips, but at night or quiet moments, the ringing is a soft and gentle sound, like someone running a moist finger over the rim of some crystal ware. Very nice in winter on a soft moonlit night
I focus on that ringing in a nice quiet and dark room, let it sing in my ears, and then close my eyes.
I then focus on the funny golden geometrical sparkles, triangles, and if I relax, a small black circle with a white border starts to show up. It seems like a 2D object, constantly rotating quickly on a 3D plane, but slowly grows bigger.
For some reason, I find these oddities comforting. The visuals remind me a bit of the pressure halo’s in your vision when you get a migraine, but without the pain, and covering the field of vision with your eyes closed only.
Once when I was 4, I let that black circle engulf the entirety of my vision as I lay in bed, and the black faded into a creamy golden background with rainbow confetti falling. Obviously it’s not really, just some other strange visuals.
Ahem. In either case, I use these to focus and relax at night to tell my brain to shut up.