Here is a visual of how I do my squares. This took me about 30 mins.
I start with a single square, then I add some lines for some squares from the corners. I fill them in when I am happy with the placement, but often need to readjust. I’m using Sotek Green, and Gauss Blaster Green for the blue.
Don’t be scared to make mistakes, its easy enough to paint over wonky edges. You can spend ages trying to make this kind of pattern perfect, know when to stop!