A crew-neck sweater and black jeans worn together are a sartorial dream for guys who love neat and relaxed styles. To add a little zing to your outfit, round off with grey leather casual boots. Keep this outfit in your head come warmer days, and rest assured, you'll save a lot of time crafting what to wear on more than one morning. Gentlemen who wonder how to pull off smart casual dressing as you are making it through your teen years, you have your answer.