Obviously, dress for the occasion. Going camping? Wear camping attire. Going to fix your car? Wear ratty clothes you don't mind tossing. Otherwise, as a general, wear clothing that properly fits you. Avoid t-shirts in favor of anything with a collar. Wear simple plain jeans for casual daily stuff if you feel it's appropriate. Otherwise have some variety in your slacks. Have some for hotter weather, different colors. Avoid logos, brands and stupid prints on all of your clothing. Get a haircut, shave, and either learn to iron daily with efficiency and speed or learn to wash and put away your clothes before they get completely wrinkled. It's not hard, just don't be a fag.