DO: Plan ahead!
If you know that your favorite actor is going to be at a convention and you just have to get a chance to talk to them, plan what you're going to say to them in advance. That way when you do get up close and the nerves kick in, you'll have a blueprint to follow. My friend Sam Maggs gives this extra-good advice in her book, "The Fangirl's Guide To The Galaxy":
"If the star is particularly well known in the nerd world for one thing, try to compliment his or her work in something obscure instead. Like, sure, you loved Tom Felton as Draco Malfoy, but if you tell him how much his performance in 'Belle' impressed you, I guarantee you'll see his face light up and get some new stories about him."
Planning ahead is especially important during paid photo ops, when you're only going to be able to get a couple of seconds with a person before you two have to take a picture together. For that, Maggs suggests doing a bit of online research ahead of time, and then deciding how to pose with your favorite according to how game they've been to pose with other fans in the past. Carrie Fisher, for example, is very game. Obviously.
DON'T: Touch them without asking.
There are people everywhere at conventions, moving as slowly as possible and accidentally bumping into each other, and it's enough to make anybody anxious about germs (or even stampedes). Add to that being in a situation where you're required to have one-on-one time with a thousand people who all enjoy your work, and having a whole lot of hands and torsos coming at you for hugs and handshakes can be an incredibly stressful experience.
A lot of celebrities have no-touching policies for that exact reason, but even when they don't, it's generally polite to wait until the other person initiates physical contact. If they don't and you're really craving some human touch, you can ask them if it would be alright. Don't get annoyed if they say no, though.
DON'T: Expect them to be the same kind of nerd as you are.
Some celebs are super huge fans of the thing they're in — if you happen to ask Ben Affleck what his favorite Batman comic is, for example, he might actually have an answer for you. But not everybody's like that, and certainly not everybody's required to be. Imagine if people insisted you should know everything about the history of "Star Wars" because you own a Darth Vader t-shirt, except all the time and even when you aren't wearing that shirt. It's kind of like that.
Plus, you might actually end up spoiling the person on the very thing they're starring in. "Game Of Thrones" star Charles Dance found out just how he'd be leaving the show from a fan, for example:
"There was a guy in the street who came up to me and said ‘Game of Thrones,' brilliant, you’ve got a great death scene! And I said, 'Oh do I?' and he told me the manner of my death."
Dance took it in stride, but could you imagine how terrible that would be if he didn't already know he was leaving the show? Better to not even go there.
DON'T: Ask them the same question they probably hear all the time.
The media is just as guilty of this as fans are, of course (hey, some of us are fans, too!) but in general you should be mindful of the big topic du jour within your fandom and try to steer clear of it. For example, if you bumped into Kit Harington before the beginning of last season of "Game of Thrones," asking him if Jon Snow was really dead would have been really annoying for the guy. Unless you were a cop who could get him out of a ticket, of course. Then you're just helping him out, right?
Same thing goes with catchphrases. You know how Jon Snow knows nothing? Yeah, so does Harington. Cool it with that, maybe.
DON'T: Be critical of something they've done.
You'd hate it if somebody came up to you and was like, "Hey, I love your work, but remember that one time you spilled coffee all over your shirt? What was that about?" or even worse, "Hey, you know that job you did that you're really proud of? It was overrated." That's just rude. So don't do that to famous people, either.
DON'T Ask them what you know them from.
Having someone walk up to you and demand you tell them why you're famous has got to be the worst experience ever. If you see somebody you recognize but can't place them in your brain, better just to leave them alone. Odds are you're not that interested in talking to them anyway other than to say you talked to a celebrity, right?
DO: Be cool if they aren't interested in talking with you.
You don't owe anybody your time, so why should a famous person owe you theirs? If you encounter a celebrity in the wild, far away from their autograph table, and your hero says she's busy when you ask her for a pic, respect that — even if it doesn't seem like she is.
If you're paying for the chance to speak with the celebrity in question, their disinterest can be much more disheartening. But even though you had a terrible experience, at the end of the day you don't know whether the celebrity is terrible as a person, or if she just had a really bad day during that convention. Try to be as sympathetic as you can, and if you're really worried about having a bad time, research ahead to see what other fans have said about the person you want to meet just in case.
DEFINITELY NEVER EVER: Objectify them.
A lot of celebrities are hotter than we are. That still doesn't give you the right to yell "Lookin' good!" at them as they walk by — that is, unless, it's Eddie Murphy and you are specifically quoting the "Lookin' Good, Billy Ray!" line from "Trading Places" at him. Even then, he probably gets that a lot, so see the above suggestion about not saying the same thing that people always say to celebs and reassess.
Seriously, though, don't say anything to a celebrity that would make you uncomfortable if someone you didn't know said it to you. At best, you are making everything awkward; at worst, you are sexually harassing a stranger. Be cool, guys.
DO: Let them know how much they mean to you
OK, so the moment has arrived. You're in front of your favorite, favorite celebrity in the entire world. Watching this person's work on TV or reading it in their comics or playing their games inspired you more than words can possibly express. But that doesn't mean you shouldn't try to express them.
If you find yourself at a conversation with someone you really admire, there's no point in pretending you're not a huge fan and that they didn't have an impact on your life. If hearing about Jared Padalecki's battle with depression, for example, helped you get through your own dark time, don't be afraid to tell him that if you find yourself standing in front of his autograph table. Everyone likes to hear that they've made a difference in someone else's life, no matter how cheesy or dorky you might think it sounds. Trust me, they'll be happy to know they had such an impact on you.