I would say the best thing is not to expect for things to go perfectly. There may be first time meeting jitters and sometimes it's a little awkward at first. Just remember that this is the same person you have seen on camera and talked to a million times. The only difference is this time you can actually reach out and touch them. Don't put too much pressure on youself.....just have a good time! And remember to be flexible - sometimes the best laid plans can get derailed and you just have to make a new, spur of the moment adventure.