Take a knife and start skinning and cutting off the hide and excess meat including eyes, tongue, etc.
I then prefer to soak them in a bucket of water for a couple months making sure to keep the skull submerged. I usually mix a couple boxes of baking soda in the water while doing this.
Then a slow roll boil till the meat falls off. Clean it up with some dawn dish soap to degrease or put it in the pot while boiling.