A recipe I've used successfully for years is: 1 ounce of sulpheric acid and 4 lbs. of canning salt per gallon of water. Let the haired or de-haired hide soak in the solution for a week, stirring daily, remove, rinse well and break. Rub in about an ounce of neatsfoot oil when you start breaking the hide and it makes wonderfully soft leather. Once it's finished smoke it and it will retain its softness if it gets wet. There is also many other suitable recipes that work just as well. Brain tanning is a great method. There is an old saying that goes "every animal has enough brains to tan it's own hide". I have found this to be true. Brain tanning makes a beautiful, white finished leather.
One thing you absolutely must do is remove all meat and fat from the hide before beginning the tanning process. Prepare your hide the same as you would if you were stretching and drying it for sale as finished fur and all will be well. Shoot me a PM if you have any questions. I've finished lots and lots of different kinds of hides for one purpose or another.
Vic