I use 10x13 envelopes for sending and I use 9x12 for my return envelopes, no folding required

Some folks fold 'em some don't. I use photo mailers for my SASE, so that means going to a bigger envelope to fit it in. I just figure it's silly to write "Do Not Bend" on an envelope and then fold it to fit inside a similar sized or smaller envelope. Besides, the photo mailer provides protection both when sending and when getting a return. Assuming I do get a return.

You need to put postage stamps on both envelopes. Never assume the other person will provide postage. I once read a blog from a celeb who stated that they will not stand in line at the post office to buy stamps to return fan mail.

How does a SASE work usually? Do you fold the envelope when you put it inside or can you just fit it inside another envelope without it being folded? I am confused on this and on the one that goes inside, does that have be paid for? I mean both envelopes have to have stamps? This is my first time doing them to bigger envelopes. so was wondering how they usually would work. thanks!