
If there is one thing students consistently underestimate, its the importance of planning. Who can blame you really, getting to see your stuff move is the exciting part. BUT! If the purpose of your animation is to raise the bar, and produce work of a standard that will get you a job, then it is inevitable that you will have to start putting some time and effort into planning. You can learn the hard way, or listen to the wise folk linked to below and save yourself a whole world of pain. Planning makes for better animation.
LINKS:

Jean-Denis Haas on the importance of having a plan.

The Spline Doctors consider different ways of planning a scene.

From the Animation Meat blog, notes and examples of thumbnailing.

Clay from the Animation Podcast steps us through his planning process.

Shaw Kelly on planning.

Spline Doctors have just put up an excellent post about the importance of getting on with your decisions when animating.

Carlos Baena has uploaded an excellent case study on how he plans a scene. (Planning Section)