I suppose I'm kind of known to be a bit more up on fashion than most of my geeky friends, because I have this conversation about once a month, and it just happened again:
some guy: I need to buy a suit for $EVENT, but I want to buy something that I can wear next time I need a suit, too. I don't know anything about suits. Help!Why do they ask for advice in the first place?
mendel: Ok. If you're just going to own one suit, you probably want something single-breasted and simple, two or three button, wool, in plain gray or navy...
some guy: No, I think it should be black.
mendel: A black suit isn't flattering on most people, and you usually wouldn't wear a black suit to anything before evening other than a funeral. Charcoal gray looks good on most people, and just by being a bit lighter you can wear it any time.
some guy: But black goes with everything, so it'll be more versatile. [goes off and buys a black suit, and ends up looking like the Guy Who Owns One Suit, Black].