First of all, I've never done it so take this with a grain of salt. I met a man who tans deer, coyote, and others hides using alum. He said alum costs 10 (or 20? not sure) dollars per pound. He has great success with it. Once he tried it with cheap "alum." ($2-3) It was a failure. So quality alum could be a factor.
Another thing, the first tries at almost everything for everyone are poor. But that's life. Practice makes better. Hope that helps and good luck, Huxley.