Took my GMAT a few days back and scored a 720 (V41 Q48 IR6). It's cold and changing weather in my area, so, my sickness wasn't surprising - too many people around are (not because of COVID). Two days before the test, I just took meds and slept for the major part of the day except for solving 10 questions each day to stay in touch. I was trying to find a debrief as to what to do in the situation but couldn't really. But just went took the test on Dolo. If unfortunately, you are in a similar situation, just give it a go. Till verbal I had energy but towards the end of Quant - well! things could have been better. By the end, I was so done physically - I barely could register that score on the screen. I will retake it sometime in the future.
I am a non-native English speaker who hasn't studied maths since 2010, basically beyond Grade 10 (I am from a sociology background and have worked in a sustainability start-up; basically nothing in my background has anything that would help me with GMAT very much) and the following are some of the things I wish I knew before I started out. So, putting it out.

Mistakes I made along the way that you can avoid:
1.
I was more than decent in school and college, I thought I could do GMAT too USING THE SAME MINDSET. Thinking the latter part was one huge mistake. I wasn't very precise on my strategy and actually built some really bad habits (and burnt questions) along the way, before realizing the change I needed:
- Every question is an opportunity for me to build a habit - good or bad is how I go about it. On exam day, we go on auto-pilot and are at the disposal of the habits we build during the practice
- I am not in it to win it - I had been playing the wrong game (if I am to steal some words from here:
https://www.manhattanprep.com/gmat/blog/in-it-to-win-it/ - I have to be very particular about forcing myself to be aware of the amount of time I spend on any question (an internal clock is really helpful on the exam day) and let go as I would do in an exam environment in every practice (Thanks Manhattan)
2.
Incorrect usage of the error log: From day one I had an error log but only later was I making effort towards actually using it properly- Spend time to ensure WHY I made that mistake to a point where I could plug it with an alternative the next time - For example, I couldn't solve this CR question, why? Because I wasn't very precise on what I was looking for in answers, why? Because I wasn't clear on the conclusion, why? Because there were multiple subjects and I didn't take a proper note of them, why? Because their first names were the same but last names were different - okay!
So Next Time: Use short forms for the name and be careful about the subjects in the passage.
I would always have WHAT-WHY-NEXT TIME for my mistakes (not written in as much detail but precisely) that would help me find patterns in my mistake as well. Sometimes, some solutions would lead to another kind of problem (talk about debugging one part leading to other bugs, haha); it just helped me take care of that.
- Not emphasizing enough on never repeating a mistake (Thanks
Magoosh). Only later did I start getting very particular about what habits I am trying to correct or build. I would get that from an overview of the kind of errors I was making as recorded in the
error log.
- NEVER refer to a mistake as a stupid mistake, even if it is a calculation mistake (why make that calculation mistake in the first place). ALWAYS replace it with something different and concrete to be done the next time.
3. Not sticking to official questions for verbal:- This has been said too often already including
GMATNinja (One of the two people I have a lot to be thankful towards). So, I am just going to say I second everyone with my lessons learned the hard way. I should have stopped once I had my strategy in absolute place but I kept practicing those for longer than I should have.
PS: LSAT questions are also better taken up only when you have a good idea of GMAT-type questions for CR. I actually found RC from LSAT really interesting and, hence, easy even though they were long but GMAT's way more dry and uninteresting.
4. Taking a course without a pinch of salt:- Now this isn't a review against
e-GMAT; it just wasn't for me. I took it up because I thought it including their personalized plan would save me a lot of time given I was working 10-14 hours a day at the time. But it cost me way more because I learned their ways that brought out my weaknesses in the worst possible ways given my background. I would always hit the accuracy in verbal in a minor time relaxed frame (a wrong way to practice once done building the approach) and overall reached V36-38 fast but timing became a major issue for me to cross that barrier. I just couldn’t make it more time-efficient without compromising on my accuracy. Then I reached a point where it all broke down and I had to start over; redo my SC and CR strategy. For RC, I always had my own, theirs was bringing me counter results. This was verbal.
- For quant, I wish I had done Veritas (
KarishmaB, especially (the other person, I am absolutely grateful towards)) or Manhatten instead. It took too much time to finish the modules - and again given my background - I was exceptionally ill-prepared for GMAT-style questions with the learning gained from
e-GMAT. I had learned the concepts but I had also reinforced an inefficient approach to problem-solving. Now if you are coming from the right background you might already be used to nuances such as trying to find the shortest way, forcing yourself to know more ways than one to solve a problem type, etc but I wasn't. So it was too much extra effort, including time-wise, for me to break and rebuild the right habits.
The point is to take any course with caution, understanding your own needs.
5. Not take into account emotional training- As I already mentioned but then I am also not sure if I am the only one, the state of mind is just completely different in the exam room. While doing the verbal, I stumbled upon an RC passage that was short but I just couldn't make sense - I read it 2 times (RC has been my strength usually) with no idea. Went to look over the question, it was the main purpose question and I wasn't able to answer that. I was there, thinking I am ****! dropped the marker for a second - re-read but now in mode to cut my losses. A situation like this with CR or SC is completely okay, I could move on easily but because 3 to 4 questions were at stake I was more stuck. But this time I was still prepared to feel the worst and yet keep moving. So, I was in very "Road ahead" mode. Once I was done, I had automatically forgotten about the previous one and was only thinking about the problem currently at hand. After I was done with Verbal, I didn't give a second thought about verbal but was re-aligning myself for the quant section and making sure I do not run overtime on break like the last time. And when I was done with both verbal and quant, I was thinking let's get ready to be disappointed with a 640-650 score but fortunately, that didn't happen. I was prepared to feel **** but keep moving, making as best decisions as I could.
These are some right off the top major points. I hope they are helpful.
STUDY MATERIAL: I used
e-GMAT initially but majority was done using GMAT Club and OG only. I would create practice sets from these official questions:
https://www.thegmatco.com/all-official-questions/ GMAT is really more about the application (decision making) than concepts at the end of the day. I bought Official mocks 3-6, hoping to retake those but retakes always showed repeated questions. 3rd 690; 4th 710; 5th 710; and 6th one ran into an error. If I knew repeats wasn’t an option, I would have used those mocks better.
Let me know if there are any specific questions! Good luck, you super people.

PS. Pardon any grammatical error, I haven't proofread.
Congratulations on the great score! Glad I had a part to play in it.