The big take away is to start early and boil down the story quickly.
Pitch with visuals of what you are looking for. Bring reference. Remember to build portfolio pieces as you go.
Play to your strengths. If you're not that strong an animator, don't plan lots of complex acting.
If you are planning to work as an animator, try to get some lip sync in. Not many of the films on Industry Day have lip sync. You'll stand out.
Watch those crowd scenes. They're a killer.