Go back to your Draft I and read over all of your comments and using unbiased discretion, choose which comments to use to improve your story text and illustrations.
Go back and make final improvements to your backgrounds. Remember to keep in mind the perspective and angle of the background. Some students want to go above and beyond and add more quality backgrounds to their story which is great. This will allow you to make more scene changes. Although, don't try to make your story extra long, it is better to have quality and keep your audience's attention rather than draw out your story and lose it because it is difficult to captivate the audience the longer it gets unless it is "killer good."
Don't forget, make sure all of your backgrounds are 720x480 px.
Move various objects in your backgrounds to its own layer if you want it to move. For example, if you are going to have the sun rise, leaves fall, birds flying, clouds moving, etc, you will want each of these in its own layer so you can move them in After Effects.
When you post to posterous, send the JPG and the AI file of each of the backgrounds. Make sure they are an improvement from the original backgrounds as I will be comparing them.