I usually carry a bright bag of some sort...LOVE Coach and Kate Spade the most (but can't afford them
) and inside is my wallet...gotta have a checkbook wallet for my cards and such...my iphone, sunglasses and eyeglasses (both in their cases), car/house keys and anywhere from 2-8 tubes of chapstick.
For school I was carrying a big ole' black backpack but I have been scouring ebay for something a bit more feminine. I saw a girl on campus with this great brown leather backpack that also doubled as a messenger bag, most likely Italian as the needlework was quite intricate. Inside are whatever books I need for that class, 1-2 notebooks for notes and scrap paper and a binder. Sometimes I will bring my laptop or iPad but only if it's a long class. Oh, and lots of pens and pencils.
In my car I always carry my yoga mat/clothes, a Conway tool kit and reusable grocery bags.