I would enclose an envelope big enough for an 8x10, just to be safe. You can always fit a small picture in a big envelope but a big picture would have to be folded to fit in a small envelope. Better safe than sorry.

A5 should be quite alright if most of the letters you are sending will be internal as most British actors tend to send either 6x4 photos or the odd slightly larger (but still under A5).

You may get larger images from actors in the US, I'm not sure.

I usually use 8.5x11 but that's just my preference. I'm sure any size you fancy is quite alright.

I was wondering what sie sase most people put in with their letters?

I am putting my own photos in when i write but I have noticed in the feedback section that often celebs send their own photo along with the ones you send them, and I was wondering what size these tend to be?

Will a5 ( think thats what the half a4 ones are called? ) envelopes be big enough?

Thanks