Celebrity signing

Approaching a celebrity can be a daunting task. Asking for an autograph can be even more nerve-wrecking! But it isn't all that bad - read on!

[edit] Steps

Remember that celebrities are just people. They have real lives and responsibilities; make sure your timing is appropriate for what you want. Fans are appreciated but keep in mind that no one wants to be ambushed exiting the lavatory stall or with a mouthful of dinner at a business meeting.
Understand that celebrities are used to people asking them for autographs. They take it in stride, so don't be too nervous.
Approach the celebrity.Don't get so close that it annoys them. Say "Hi," tell them your name, and give a light compliment. Do not gush - they don't enjoy it. Ask a question or two. Comment on their latest movie, video, book, or whatever they're famous for.
Ask for an autograph by saying "I'd love to have your autograph," or "May I take a picture with you?" Don't be shy. Be confident and smiley.
Hold out a pen and paper, but don't stuff it into their hands.

[edit] Tips

For whatever reason, it might make you feel more comfortable to ask the celebrity to write their autograph so you can give it to your friend or a child. If so, you could calm your nerves by asking in this manner.
Also, if you do the above step, you could tell them to make the autograph out to your brother / sister / girlfriend / child while actually providing them with your name.
If you can't summon the courage to ask for that autograph, you could always try to buy one through an online auction or at a memorabilia convention.
It is advised not to get clothing signed, marker and pen usually goes out after a few washes, even permanent marker won't last forever on cloth!

Try to tone down your smile! When you look at most pictures with celebrities, you will notice that the non-famous person's smile is much wider (and probably dorkier) than the celebrity's. Why? Because you're overcome with excitement and for them, it's just another photo. Be happy that you get a closeup, but bring your smile down just a couple notches.
One item only! Celebrities will think you will be selling stuff on Ebay.
Do not get upset if the celebrity says no. It may not be a good time for them to sign an autograph or take a picture. It is very annoying to see a fan over react and you may be escorted out of the area.
Never ask while the celebrity is eating dinner or spending what looks like quality time with family.