I don't think there is a guideline to success in this thread. It is more about just what you are wearing. It is more of an art than a science. There are socks that are totally unrelated to both shoes and trou that look horrible and socks that are unrealted to both shoes and trou that look great. I guess just complimentary pairings. Also, I would note that style of trouser, sock, shoe is just as important for the combo to look good as colors are.