Place an ad looking for a fur buyer in the sporting goods section of Craig's List. Also check your local newspapers classified ads, and/or contact your state trappers association or fur havesters association.
FYI prepping your furs for sale does not require tanning.
Make a fleshing beam just a tapered piece of wood to lay your furs over. for the Coon, just use a cheap tavle spoon or serving spoon. The coon will scrape really easy. remove all fat, and excess flesh from the pelt. At that point just stretch it on a wood or wire framed stretcher.
Wire framed stretchers can be bought at almost any sporting goods store. cut the belly fur out of the coon in an oval shape from the legs up to the penis. after that just put it on the stretcher and let it dry.
The Otter will require almost no scraping. they have very little if any fat on them. Sometimes some excess muscle tissue needs to be removed between the front shoulders but only if it didn't come off during the skinning.
I prefer wooden boards for an otter because the tail needs to be laid open and tacked from base to tip. you can buy wooden stretchers online at various trapping supply houses. PM me or Preacher he'll have the info.
Beavers are a different story. wicked pains in the heiney to scrape.
you'll need a specific fleshing tool. There's no easy way to flesh out a beaver pelt. Just go after it. I've found that starting in the middle and working toward both ends is best for me. The fat over the tail is the toughest you'll find and comes off hard. Once you have the pelt free of fat, and tissue start by nailing the nose and tail on a pice of plywood, then each side so your pelt looks a little bit like a square. Then split the difference placing a nail at the half way point between each original nail.
This will take a while and stretching a beaver is more of an art than other furs. Your beaver pelt should be nice and tight and be in a circle shape when your done.
Once these furs are dry, you can sell them. Our state requires Otters and beavers to be tagged and sealed by a game warden prior to sale, so check your regulations.
If you handle fur properly, and present it well, it will command a higher price at the buyers. Good luck.
Mojo Mallards are gay