Before I got my current job, the biggest thing I flew was a Cessna C206 dropping skydivers. Here is my experience doing a type rating on a Turbo Prop.
The Ground school was 2 weeks followed by the examination. I could go into the details of the groundschool but I'm sure the main question in this thread is to do with the fllying/sim section of the type rating.
We (Myself and another collegue, me with 410 hours total and he had about 600 ish) had two weeks of the sim with a session every day of 4 hours (2 hours in each seat). After the first session of which it was getting used to "flying the aircraft", we came out with a feeling that it was impossible!!! Our instrument flying was terrible and speed control, altitude control was not brilliant either. The next session proved much better as we rehersed all the things we were meant to do in our hotel rooms etc. I was very much a confidence building excercise. It was only after the 3-4th session of the sim that we really got the hang of flying the sim but then came the emergencies. Each session got progressively more difficult in terms of emergencies etc
The thing that I do to prepare myself is i do alot of visualisation so that always helps. Just towards the end of the training, we worried about how we would do in the test/check. Everything was fine up to then but maybe you go into a self doubt period, i don't know. Come the day of the check, all went well and we passed.
The only thing I can think of for not passing the check is that of Self Confidence. Another would be other factors like the state of your personal life, problem in the family etc. You really don't need that sort of stuff distracting you when you are trying to do the sim.