A book on getting in service academies would be a waste of money, in my opinion. My USMA grad followed West Point's application instructions to the letter, as well as his MOC's instructions, he met all of the deadlines, and he got in with no problems. He had a great MALO and was able to meet with his Admissions Rep at West Point one time and he did everything everyone told him to do. He took the ACT multiple times and worked hard in school.
We didn't even know about the SA Forums until several months before Beast, long after he had been accepted.