http://www.ssa.gov/disability/professionals/bluebook/12.00-MentalDisorders-Adult.htm#12_10
carefully read it, know the qualifications and buzzwords and base your appeal around it.
its not necessarily true that everyone is turned down the first time, but plenty of people are, and the appeals process is there for a reason. take full advantage of it and include every last piece of documentation you can, including school evaluations and his IEP if he has one. and of course every report ever generated by a doctor, therapist, whomever.
but dont give up--its a long process.
