For formal or business: Do not wear blue with black, just don't. You'll look like a bruise.
Obviously on a Saturday, Levi's and a Harley T-Shirt are fine...
(Also never ever wear brown unless it's tweedy and you're going shooting in the country on Sunday.)
If you've not yet got a decent wardrobe of suits to choose from, start by buying a good black one or dark grey or dark blue one and get the best white shirt you can afford.
If you buy a black suit, wear only white or grey and red etc with it. If you also have a blue or grey suit, you will be able to co-ordinate blue and pink and purple...
But whatever you do, please shave. My only current outstanding opinion on men's fashion is about this nasty new fad they're having with the 3 day-growth. Dreadful.
xL