Just have fun (and get there early...)
We went to DisneyLand this summer with dds 4 and 8. Youngest and I spent a lot of time finding the "I changed my mind" exits :P But she had a *great* time. The character interactions were amazing
For collecting autographs...we brought Crayola color wonder pens and paper and that made it even better, the "masked" characters can't talk so they had to gesture their enthusiasm. Very amusing. Wonderful memories.