I like scrappy, but I think you do need some variety to get some visual movement. So I would make sure to include some lighter fabrics. If you are short, maybe you can go to the trading section of the board and ask to get some from people. Then you have a better variety.
I agree with assembling 4 patches and then making those into 16 patch blocks.
I have a bag of 2 1/2 inch squares that I got with a sewing machine. I use them as leaders and enders and making 9 patch blocks. I try to be random but I find myself doing a bit of lights and darks like you would a regular 9 patch pattern.
Look forward to seeing pictures of your progress.