OK, if you've never met Jim at a convention, there are very important rules to follow.
First of all, do not look Jim directly in the eye. He will run around the con screaming that his soul has been stolen, and it'll take them at least an hour to calm him down.
Stand downwind from Jim. He's very proud of his cologne, which he makes himself. Compliment him on his unique musk at every opportunity.
Do not turn your back on Jim when you leave the table. Instead, you will be instructed to walk backwards, bowing on every third step.
Do not speak in plain English to Jim. You must rhyme.
Do not believe a single thing I've typed above. Jim's one of the friendliest, most down to earth people you can ever meet, celebrity or not. The man's genuine, friendly, and damned funny. I'm looking forward to seeing him again.