I pin them to a board with T-pins, flesh side out. Put your pins at least every 2" apart down both sides. Don't stretch the skin very much either, since that leaves gaps between the scales and IMO, only looks good on copperheads.
Pay attention to the scale pattern when your pinning it too. Don't distort it by stretching one area more than another.
After you get it pinned, gently scrape any remaining meat/fat/blood off with a fairly dull knife or spoon. I've found it works better to scrape from the tail towards the head for some reason.
Place it in front of a fan for a day or so. Then after that, you can put it out in the sun for a few hours and it should be dry. Once it's dry, cut down each side, just on the inside of the pins and she's done. I usually measure 'em, label 'em and roll 'em up after that.
Hope this helps,