If you can, get or make an autograph book before you arrive. Sometimes Mickey and Minnie will be waiting just past the entrance and if you don't have the book, you'll miss a photo/autograph chance.
You can even pick up a small notebook and decorate it.
If you come across a character line that is too long, you can always skip it. I think autograph books are a blast and make for some good memories.
ETA: You can find some sellers on Ebay or Etsy that make autograph books.