1. First and foremost: LEAVE YOURSELF ENOUGH TIME. Do not get caught up trying to answer some stupid MCQ that you are convinced the right answer is not there. Just pick an answer and move on. Leave yourself PLENTY of time for SIMs. I usually spent about half the time in any of my exams working on SIMs
2. Completely agree with Kricket– learn to use the Auth Lit. It helped me immensely with all three sections, and especially AUD. If you leave yourself enough time, you'll have time to search for things in the AL and will be able to read through things slowly enough to be able to think through the information. I don't know about you, but I can't research in a time-crunch panic.
3. Comprehension of journal entries are key. The couple of days before I took FAR, I went through my becker book chapter by chapter, and copied down every single journal entry in the book. Yes its possible you'll get a SIM on a topic that doesn't have a ton of JEs represented in becker, but in copying down all the JEs for all the topics in the book, you start to understand the logic behind them. When you are taking the actual test, try to think through what is happening if you get a SIM involving JEs. Is an asset account increasing? etc.
4. Know your stuff on governmental/nfp, because there is not AL for govt, and you may still get a sim on a govt/nfp topic.
Now that I've taken all four parts, when I look back on my experience overall, there were always, in each section, *details* of topics tested in the SIMs that were not in becker. My thought on the AICPA's approach to SIMs is that while they do test the some of the major concepts, by throwing in these weird details they also test your ability to reason through situations you would face as a public accountant. Just my two cents though.
REG- 53, 91
BEC- 88
FAR- 62, 85
AUD- 85
Ethics- 93