The last thing you want to do is add more bulk to an already larger frame. So on crisper days, opt for a sweater with enough thickness so that you can leave your jacket at home. Boss Piceno Mock Neck Sweater ($125) in Black is a classic style with a V-shaped contrast placket that will draw the eye up and down, elongating your neck. Avoid crewnecks when you can. A round neckline will just make you look…well, rounder.