I've tried many kinds of fish skins,and treat them all the same.
Scaled fish(carp, etc) must be scaled before you skin them.
Scrape/flesh skins very well,being sure to remove all oil pockets.I scrape with a fine serrated butter knife,kinda works like a tootheing plane.
Scrub skins with a stiff brush and in dawn dish soap,rinse well,wash again,rinse well.
Keep both sides of the fish together,cause colors/patterns vary between fish. measure and freeze,being sure to label them.
I've found that fresh skins lay down alot better than dried skins.
If you have to dry them, lay them out flat on a slick board of such.I like cabinet shelving,(melamine) ?(sp), It's very slick and the skins,once dry will come off better.With the flesh side down,and tack them out,stretching as you go. Keep your tacks close and you'll get a better job.Keep a fan blowing air over them and they will dry perty quick.After dry pull tacks,trim edges,roll up and store in a freezer bag.No need to freeze them for they will keep. Apply them like rawhide.(I always thin mine on the belt sander before I apply dried skins.)
A note about grass carp skins if you are gonna dry them: Once tacked down take a dull putty knife and run it down the skins along the scales,(head to tail) It will lay the scale pattern in place.
If you apply raw skins,it takes alot of babysitting until they set well, so make sure you have plenty of time.
Some of you noodlers out there need to be sure and keep you flathead skins.Really cool stuff there boys,and tough as ground hog!