Use a needle and syringe and inject luke warm water and a couple drops of dish soap in it, once it is rehydrated, clean all the meat and fat off, use borax while doing this as it helps soak up the grease. Then soak the feather quills in a glass jar of acetone enough to immerse up to the skin, can do this a couple times to degrease. Then bath the entire tail in warm soapy water, remove from water and wrap in a towel to get most of the water off, then blow dry with a hair drier until completely dry, this will take a while but they will get real fluffy when done. Then lay tail out on a table they way you want it to look and mix up a little body bondo and put it on the feather quills, let it set up and trim excess. Then flip the tail over carefully and bondo the back side of quills, trim and let it harden. Rub some borax into the skin to preserve and let it dry. Most important is to get it clean and degreased to make it look good.