The cloche is the retro shape of the season, but its bucket shape can swallow your head and make you look bald if you've got a pixie cut. These work best with bobs or longer hairstyles, and longer faces (the width will unfortunately overemphasize rounder features). Check out this cute tweed version from Lord and Taylor.
Or this cute pink corduroy version (pins not required).
Depending on its structure, a nice beret can work well with different head shapes. This looser fitting version is great for softening a more square jaw, but you'll need long hair if you don't want to look like you're wearing a scrub cap. Also, don't forget that hats are a great opportunity to add some color to your outfit. This yellow is a great example -- totally vibrant, but still neutral enough that it won't clash with your coat.
This more traditionally-shaped beret can be worn with short hair, plus its looser weave and hang will balance a rounder face. The texture adds pizazz to basic black (or check out the seaweed version for a little more color).
The firm brim of a newsboy hat works for a number of head shapes and hairstyles -- but make sure you try before you buy, as some brims are wider than others (and a brim that's too wide will overwhelm your face). This fleece version from Target is narrower and has a cute bow to boot.
If your head is on the larger side or you've got a lot of hair, try a newsboy with a fuller cut (but still a narrower brim).
There are a host of adorable hats with ear flap out this season, and not all of them come in gaudy colors or look like gear for a hunting expedition. Sure, these hats are more 'playful', but if you keep the style simple, they can be both warm and stylish. They'll work with most head shapes -- just remember that short hair requires a short ear flap so your head doesn't get consumed. Here is a cute one that would suit most hair styles and head sizes.
Avoid hats of the nubby, hand-knit variety or risk having your headgear steal the show. Remember: The idea is to integrate your hat with the rest of your outfit. This one is delightfully understated and comes in whatever color you need.
While it's often dismissed as childish or unfashionable, you can't discount the old pom pom. Depending on its shape, this hat can accommodate a longer, thinner face as well as a fuller, rounder one. If your face is on the rounder side, go for something tall and pointy -- like this one in vibrant blue.
Lastly, a narrower face can carry a thicker knit and a rounder shape, like this cutie from Moose Jaw.
The point is: Never miss an opportunity to make a practical item really count in your overall self-presentation. Any accessory can be helpful or harmful depending on your shape and stature, so keep these tips in mind when you're staying warm in your winter hat!