I would say that plaid dress shirts, leather jackets/bomber jackets, v-necks or long sleeve shirts look great on men. You can always add accessories as well, such as scarfs, hats, or ties. Make it casual yet sophisticated.
For young guys I think preppy is the best. Sort of what Chuck Bass and Nate Archibald wear on Gossip Girl, like dressing shirts, even in bright colors and sweaters. Skinny ish jeans are the best, but don't over do it!