Well, here is a set of queer eyes for the straight guy.
socks should match your pants, not your shoes. If you wear black pants, black socks.
If you are on the thinner side, shirts tucked in, if you are on the heavier side, shirts untucked.
Try to make one smooth "line of color", which will make yourself look taller. Example: Black jeans, black t-shirt, with a striped or patterned button down on top, but unbuttoned. The black pants and t-shirt will make you look taller, while the other shirt adds color.
AVOID horizontal stripes. They make you look heavier.
buy for your size. If you are a "large", don't wear "Extra Large", as the extra material will make you look bigger.
Look for colors that work with your skin tone.....neon orange is NOT the way to go.