I bought a surgical "pen" and marked 6 dots on each side of my abdomen. I would alternate
Left abdomen side, left 1 dot side
left, left 3
left, left 5

then

right abdomen side, right 1 dot side
right, right 3
right, right 5

Then
left, right 1
left, right 3

and so one until I had done 24 separate sites. Then start over again.