I have sold hundreds of craft books on Ebay and Etsy. Small thin books I put in a plastic bag, sleeve with cardboard and ship in a shipping envelope. Larger books I do the same thing, but ship in a box. And on each item shipped, on the left hand lower corner, I write the dimensions, underneath that the weight, and underneath that the class of mail: either media or GA. If the buyer has paid for priority, I will slap a few priority labels on it.
I have never had an adjustment in the las 15 years or so. Before that, when I first started selling and learning the rules, I shipped so old comic books media mail, and they were returned t me as being not eligible for media mail.
