The rules say "use 4 colours only".
I recommend that you find a nice tint and go with a light-to-dark palette.
I've started but I might give up the screen size is pissing me off
It really boils down to "git gud". With that said I'm not sure what your problem is.
Mind posting a screenshot?
I've given up now but basically all my plans would be ruined by too large graphics or text ect.