You need to start reading a book about applying. The one I read was put out by lawyers. I think it was from tha "Nolo" series. One of those books will tell you: Put down every single ailment you've got, mental and physical. Relate every one to a "functional" inpairment - meaning the ailment interferes or makes it harder to get things done.

They will also want to know what you've done to get treatment for whatever is treatable.