Next month will be my 12th cruise, and I'm taking a couple of pillowcases, and dropping them off at guest services to be autographed by the characters. This will be the first time I've done this. And I want advice from the experts. I'm thinking a white pillowcase, and a black marker. Should it be a fabric marker? Is a permanet marker just as good? Should I get another color marker? Thanks in advance for the info.