Depending on the Project, your shot has most likely already been planned out. Check out any Storyboards, Previs, Animatics, and/or Editorial Cuts. Make sure you know the purpose of the shot. Look at the surrounding shots for continuity. Find out where the character came from and where he's going. Make sure you have a clear understanding of what it is you're needed to do. Make a list of any questions you have so you have them handy for the Discussion.
Talk the shot through with your Supervisor, the Director, or your client until the idea is clear. Make sure you understand their interpretation of the purpose of the shot. If you have some initial ideas, this is a great time to bring them up to make sure you're going down the right path.
Take a look at the character(s) model sheet(s). Are there predetermined looks that you need to adhere too. What is the particular style of animation. See if there are any motion tests that have already been done to develop the character.