I rotate my site around the tummy area.
I adopt the policy of odd numbered dates = left side and even numbered dates = right side.
I very rarely use my thigh as I was advised walking would increase the absorption rate and I walk a lot.
Being slim, I need to pinch to inject. As I am not double-jointed, I have never pinched and injected in my arms
I bruise easily so within left and right side of my tummy I can usually see (and avoid) recent injection sites and inject at least 2cm from the bruises.
If I was logical, I could probably devise a technique for selecting injection sites (e.g. top left, middle far left, bottom left, middle centre left).
After 15 years, I have no lumps from injecting.