Agreed, Bob.
Don't ever take your helmet off in public. It kills the whole illusion for everyone. Once they see that you're just a normal-lookin' guy in costume, they'll relate to you in a much more relaxed fashion. You're no longer Boba Fett.
But if you'll just stand there cradeling your rifle with a cool, menacing demeanor in a movie theater as the crowds stroll in, occasionally giving a slow nod to someone who waves or speaks to you, you WILL be Boba Fett.
It's really quite amazing to be in that suit. Both kids and adults will gather around you to marvel at the detail of your costume. But they never want to get too close. They all tend to keep a respectful distance because deep down, they are intimidated by your appearance. It's actually funny to watch, because you'll see people actually checking each other's distance from you, because they don't want you to single them out for getting too close. In fact, the kids prove to be much braver on this front than the adults.
People will try to speak to you in an attempt to relieve their own anxiety about being confronted by a faceless assassin. They'll ask you things like, "Wow. You put some time into this costume, didn't you? How long did it take?"
Don't answer. It's not a costume. You are Boba Fett. Simply look away slowly as if you couldn't be bothered answering such a question.
People become soooo uneasy when you won't speak. And it makes the experience so much more real for them.
The only time you should speak is if:
a) You have a good voice/speaker setup that keep your voice in true character. If not, don't say anything.
b) If you have something very "Fett" to say. And this doesn't necessarily mean quoting movie lines. But if after several failed attempts at getting you to speak, a person finally asks you, "don't you ever talk?", you simply lean slowly into that person's personal space, pause for a moment, and then say, "...When I have something too say.", and then proceed to return to your ready stance.
Be creative. But be minimal. Less is definitely more with Fett.
~Brian