jordangirl - 2 stamps will be just fine. That's what i've always put on mine when requesting one. I have never actually sent out a playbill to be signed - i've always just asked for one, and they've always sent it

! Usually I'll ask for a signed playbill and a signed picture, and about 90% of the time I've received both.
SgtDonut- Many of the performers I've written to, I have never seen perform in real life. I just usually like the show they're in, or something like that. (I live in MN, so seeing shows in NYC isn't exactly the easiest). Anyway, I try to look for video clips of them performing online so I can comment on their performance in some way. I always have a boatload of questions - they always go unanswered, but it fills up writing space. Lastly be sure to ask for an autographed picture, or whatever you're interested in receiving. Include a self addressed stamped enveloped (6"x9" is fine - 2 stamps if you want a playbill, 1 stamp if you want a pic). You can fold the envelope sideways and stick it into a business sized envelope with your letter. I'm telling you all this because I was clueless when I first started writing, and it took a while to find out all the info i needed to know. Anyway - it's a fun hobby :)! Feel free to PM me if you have any Q's. GOOD LUCK!