I was a repeater as well.
Passed October 2016 Mechanical - Thermal Fluids.
To reiterate what has already been said.
The biggest thing I believe got me over the finish line this time was truly understanding how to recognize problem types and the proper theory/method to solve the problems.
When I started back studying after the April exam, it was like I had never worked some of the problems in the NCEES and 6 min Solution practice exams. I made an effort this time to examine each problem and say why I used certain equations. For example, when to use hf vs hg, how/when to use "mass flow (in) = mass flow (out)", and especially when to incorporate the efficiency of a turbine or boiler, and when not to.
I shamefully admit that I took Dr. Tom's Classroom course for my first try because his class really is top-notch. I still highly recommend his class because I still used his weekly lessons in my prep this second time. The MERM, Dr. Tom's Exam Day Companion, and his practice questions that his gives out about 3 weeks before the actual test were the main resources I used during the test.
Hindsight, I would have probably been successful the first time, if I had completed a crash course upfront, then went into working the practice exams over and over until the exam. Dr. Tom's class finishes about 3 weeks before the actual test, so I didn't really work the problems over and over until I was doing them in my dreams like I should have done. Dr. Tom definitely has a gift at teaching. He is silky smooth in how walks you through how to solve problems in all the topics. He also throws out certain problems in the Six Min Solutions practice exams that are really not good exam problems -which helps a lot. His advice on which specification to take is golden as well.
I wish he was at Clemson when I went through, then maybe thermo and heat transfer would not have been so terrible for me. His weekly lessons are very clear and well explained to where I falsely gauged myself as understanding the problem but I really was not there in my understanding. As I prepared working problems for the Oct exam, I had some "Ah ha" moments remembering problems that stomped me during the test that I wished I had back.
So basically first you need to be real with if you can truly teach yourself or if a course is needed to do this. Get the theory from self-study or a course, then rework the practice exams and as many problems as you can, over and over and over again until the binding fall off!
Having the NCEES 2001 also helped me see that I didn't truly know how to apply certain principles because it exposed me to additional problems that had the same theoretical undertone, but they still stomped me, illuminating the fact that I really didn't get it yet.
Lastly, during the test, have as much of a calm spirit as possible during the exam so that your mind will be free to use commonsense and sound engineering assumptions. I was amazed at some of the problems that I deemed "hard" during my first pass through which ended up not being so bad.