Good one! Yes, I created a bunch of postcards with characters on them and info on the back, like trading cards. I spread them out over different festivals, so they’d be fresh images at each one. I also sold them as packages at comicons for 2 bucks and we sold quite a few.
Most importantly, have someone there. The more involved with the other people at the fest you are, the more you’ll get from it and people will know your stuff and then cross promote it.