If you are serious about a career as an artist Don't try mail art. don't even send a postcard.
Sometimes I sned postcards to myself simply because I know that I'm likely to get a favorable response.
Whenever the source for collagable material plays out--I usually turn to the trash that comes from out of my mouth. The mailbox is a bottomless pit.
( and this is my favorite--my comment)
Anything I ever sed in my life (that had at least some significance) usually rubbed someone the wrong way.
I love this guy. He's like the Jay Leno of the Mail art world--needs a drum beat and cymbal at the end of each line!