@simpleD hit the nail on the head. Form, anatomy, motion, time, basically anything and everything you need to know to be a good 2D animator will factor into 3D as well.
Software wise, you may want to pick up trial version of Maya or 3D studio Max, depending on what your class is going to use, and a lot of times you may even be able to get student versions for a far lower price than the professional versions. Blender’s good too, but the interface is very different from other 3D programs (that I’ve used, anyway).
Another good idea is to read up on set lighting and scene composition. Lighting in most 3D programs is just like set lighting except you don’t have to worry about mundane things like heat or gravity, and can add an extra impact to an animation. Composition will also help add impact, and help you focus on the important aspects of a scene while saving time (why animate something that isn’t going to appear on camera?)