Well, it is up to you, but i'd recoomand matching the clothes properties with the character personnality : For example, if your charachter is Violent, go for a red t-shirt, provocating labels, jeans with holes, spikes, bandana... and if the characher's shy and closed, Go for grayish colors, hoods, very closed clothes like a cape, long jeans, and if it's always happy go for a green/yellow shirt with fancy drawings on it, fresh bracelets and nice looking hat maybe.
If two characters have got the same emotions, go inspirational and differ. One happy boi is different of another.