A really easy one that looks really classy when finished:
1) Wash hair, then dry 3/4 of the way.
2) Gather two medium sized sections from the sides of your scalp and braid back to 3/4 of the way down your head.
3) Put the two sections, as well as the rest of your hair into a pony tail.
4) Pull the pony tail through the holder to form a bun, then adjust the ends so they splay out slightly.