For their hairstyles? Depends on the mage. One of my associates keeps it shorn close to the head and wears an impressive horned headdress. The Dalish keepers I've met tend to favor simple updos to keep it out of their faces. Qunari mages... well. That depends on their handlers, I guess.

I've noticed most novice Circle mages tend to keep their hair short to avoid burning the ends early on.