Okay, for me specifically, I had six hours of testing. It started out with a seemingly non-specific questionnaire on anxiety, depression, substance abuse and other random psychological queries. Then we took the WAIS IV IQ test, which took quite a lot of time. This test consisted of mental math, story problems, solving visual puzzles using both blocks and images and much more. Then we did the House Tree Person (or whatever order) test. Then I took the ADOS and answered some more specific questions that were autism related. I'm sure I'm missing a few things but, overall, nothing to be worried about. I would highly recommend bringing in some prepared materials. I'm not sure how crazy you should get with it but I ended up typing around 12 pages, single-spaced on what I've struggled with, what I thought my symptoms were and how they affected me, etc. During the diagnosis session, I asked them and they said they really appreciated the extra material and that it was extremely interesting. I then asked if my diagnosis would have been the same without it and they said absolutely, so though it doesn't seem totally necessary, I think the psychologist would appreciate it (or never actually read it, haha). Lets see, my Mom also had to fill out two question forms and that was it. No big deal, as long as they're competent. I had massive anxiety before my testing due to all the unknowns, but in perfect hindsight, that was a ton of energy wasted.