What I did was take my kids to places like Chuck E Cheese, where there were characters just to see how they would react and to reassure them not to be afraid. For DS we went to Hershey Park a few months before our trip. He loved all the rides and wanted nothing to do with the characters up close. He would stare at them from a distance! It wasn't until this past trip that he wanted to take pictures with them(3 years old). But that gave us a trial run of what it would be like in a park with him. I also got them use to sleeping in their pack n play about a week before our trip so that they would sleep in one at the resort without a problem. That worked for DD, but for DS we were lucky that the resort had a full crib waiting in the room for us.(I did request it, but that doesn't always work out) Also, I got my kids, when they were infants use to drinking a room temperature bottle a few weeks before the trip.