Not sure I can answer your questions as I’ve not done this but I would think a limited color palette spread around the blocks would be one thing. Pick a Focus fabric and work off of that. I don’t think every block needs to use all the colors but any color should be used in three or more blocks and the Focus should be in every block.
Then pick block patterns in a similar way. At least 3 with similar lines, in a very broad way— stars, angles (like wrenches), curves, stripes. Quilter’s Cache would be a good resource for the block patterns.
Just what I would do. Certainly not the only way.