1. The Knit Cap: Besides keeping your noggin warm, the knit hat is a casual classic that's pretty effortless. It works with any length of hair but looks best when a bit of your locks are peeking out. If you have bangs, sit your hat back and sweep bangs to the side; for straight or shoulder-length hair, try the wind-swept messy look (spray hair with a texturizer first); and for longer hair, go for easy waves (pump up waves with a curling iron and hair spray) or a side ponytail.

From left: The North Circular Cable-Knit Wool Beanie, $95, available at Net-A-Porter; Pieces Stripe Jersey Hat, $17.24, available at ASOS; Wooden Ships Slouchy Beanie, $28, available at Urban Outfitters; Eugenia Kim Montana Buffalo Check Cap, $188, available at Shopbop.