I'm rather confused about the issue of stamps, and packaging.
Specifically, I intend on sending fanmail and autograph requests to several American celebrities (especially Christian Bale; Baleheads represent!). I live in the UK.
I am wondering what the best thing to do is.
Firstly, I wonder what kind of envelope is best to get. Should I go for 8.5x4 inches, 10x8 inches, or 9x12? Will celebrities have a variety of picture sizes that they can choose from when presented with an envelope of a certain size? I am not bothered how big the picture will be, but I do not want to not get a response because my envelope is too small. Nor, however, do I want to spend more on postage than I need to!
Secondly, what is more cost efficient/simple in terms of postage: should I attempt to order American stamps online, or should I use IRCs? Which will work out cheaper? Will sending IRCs be a pain to the celebrities, or are they okay with it?
Additionally, is there any easy way to figure out exactly how many stamps or IRCs will be enough? Or is it essentially a guessing game? As an estimation, roughly how many American stamps or IRCs do you use (and which kind of envelope do you normally send?).
Sorry for the deluge of questions, but this whole hobby looks like so much fun I can't wait to get stuck in. Also feel free to share your enthusiasm by telling me about your first autograph collecting experience!

Thanks all so much!
~ Sarah