I started out with the idea for formula sheets - thinking I'd want a bunch of them in my binder. I quickly realized though that they aren't all that useful if you haven't worked problems with them and familiarized yourself. I went the route of focusing on practice problems and practice exams. They key was that I wrote out long form clean solutions to each one, and I would write out the formula I used and put a box around it so it was easy to find in the solution. Throughout the solution, if I used a formula or code section, I would explicitly write it out and then box it. (i.e. I would write the formula FIRST and then below it I would re-write it with the numbers/values specific to that problem in the right place, then write '= ___' and continue down the solution. I then sorted these problems/solution sets into sections from a table of contents I created. In the end, I never used any 'cheat sheets' or 'formula sheets' but instead went to the section of my binder that was most similar to the exam problem, reviewed the problem's I had done in my studying, and then used those solutions and the formulas/methods in them to solve the exam problem. This worked really well for me. It's hard to summarize in a single paragraph - I wrote the whole method up on
this website. You can also download my Table of Contents from there. However, I would recommend editing/adjusting the TOC to match the most current exam subjects (published by NCEES). I did put formula sheets from
Engineering Pro Guides technical study guide at the beginning of each section for reference if I knew how to do the problem already and just needed to grab a formula. Also as an option for 'hail Mary' attempts at solving problems that I was totally stumped on. I think the key here is not to start out with the idea of collecting formula sheets - but to start out solving problems and then collect relevant formulas in a place where you know how to find/use them.