Pixar Canada has some great advice on Demo Reels.

An application that requires a demo reel submission has 4 parts:

• The cover letter
• The resume
• The demo reel
• The demo reel breakdown

Great advice that can be applied to animators:

• Your reel should be no more than 4 minutes.
• Don’t show un-approved work.
• Nobody cares about music/soundtrack.
• Put your best work first.
• Include a title card at the beginning and end with your name, address, phone, and email.
• Show work that proves that you know what you did.
• Take the time to polish.
• Show it to other people.