just use similar materials and colors. if the house is tan, make the garage tan, use the same type of shingles/colors. get the associations input on it early on so you know what they have issues with, they usually have a good comment or two and that makes them happy to have some input. You have to give a little to get a lot sometimes. my favorite comment from them was "why does it have to be so big?" I almost laughed right there. They also wanted a lot of windows, which as we all know from some of the other threads on here, take up valuable shelf space, but I told them I would put some in per there suggestion, even though I was planning on putting them in anyway.
have some good elevation prints available, not chicken scratch on a napkin of what your ideas are.
Good luck