Do's: There's something about a guy in a plain white tee that I think is just timeless and classic. Sure, it's meant as an under garment, but I find that it's a basic that is also a statement piece. It just confidently says "I've got style and I like comfort." It's perfect for summer and can be worn with just about anything.
Don'ts: If there's anything I dislike most, it's this trend of men being super obsessed with wearing and talking about fashion. Louboutin this, Givenchy that. Men have a right to fashion, but personally, it's a major turn-off when a guy is dripping in trends and can name all the luxury goods I'm wearing by season and designer. Do you boo, but play it cool.