My best advice for REG is to understand the fundamental tax concepts you learn such as Corporate Tax, Partnership Tax, Property Taxation, etc. and when getting a question, being immediately able to identify what you are being tested on. This will save you a ton of time as you will immediately know whether you know the concept being tested well enough to answer the question.
As for specific content, C-corp, S-corp, Partnership, Individual, and Property Taxation are all musts. You need to have an 80-85% understanding of the material. I'm not sure whether the review course you are using to study gives tips for which areas in taxation are tested heavily but from my experience, know basis VERY WELL and for ALL the tax topics. From practice questions testing your knowledge in taxation, pay attention to what you are asked for and focus on UNDERSTANDING, not just memorizing how to do something. Memorization of major topics only becomes an option when you have exhausted all your efforts in learning the material and still do not understand it (it happens so do not panic and try to make sure this happens in areas that are not as heavily tested. For me, this was advanced questions pertaining to estate and trust taxation).
Another tip is to master the fundamental questions for ALL the study units/topics. I got some estate/gift/trust taxation questions on my exam but the questions were fortunately basic and just required some good memorization and a little bit of application but nothing too complex. Please do not ignore business law and answer questions that ask you to APPLY a b-law concept to a specific scenario (these are harder than the b-law questions that test your memory of certain terminology).
Do realize where you can earn the most points. B-law memorization questions that test your understanding of certain terminology are great ways to earn points so become familiar with terminology.
Finally, practice sims. On the exam, the sims I got were a bit harder than the ones I got in the Gleim Review System. Think of them as multi-step MCQs that require you to put more effort in deciding how to proceed. Save yourself 2 hours for the 8 sims at the very least. I forgot to mention this but do not focus on memorizing all the tax credit phaseout limits. I had a fundamental understanding of the tax credits and memorized some phaseout limits that I felt could be asked on the exam. This should be the very last thing you focus your efforts on.
Apologizes for the long response but I hope this helps. While I cannot disclose the quantity of specific topics I saw on the exam, do know the AICPA blueprint for REG is quite accurate for the content area percentages on the exam. Study smart, not hard (do not study when you are getting tired as you will not retain much of what you study! Take a break.) and best of luck on your retake.
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