I think college is a place of the '3 clothing rule', meaning the maximum articles of clothing should be three. As you don't want to faff around will lots of different pieces, nor do you want to be cold during class
This could be jeans, t-shirt and a plaid shirt (btw Plaid shirts- ladykiller!) Or, if you're fancy: Trousers, shirt and tie.
Either way, try not to SCREAM with style, or be the guy that wears t-shirts and black jeans everyday. Try different patterned shirts (with a comical pattern?), different colours jeans.trousers (Different colour trousers can totally change your whole look, and make it look like you have variety even if you've been wearing the same white t-shirt for 3 days)