Crazy genious thanks for the congrats!
First of all, know that I feel very humble about my score and that there's definitely a lot of brilliant people out there who can help you achieve your desired score. That said, I think the main advice I can give to others now is that, since we are all different, that which worked well for someone else might not necessarily work for you. I have an undergrad degree in Math, but to be honest I had to work seriously in the timing thing for the Quant section, the thing is I love solving problems so much that I simply couldn't help but try to answer correctly EACH one of the questions, by the way when I started my prep I used to write a lot for each for question, dude! my mathematical formalism was fostered for 4 years. So if you find yourself running out of time very often get yourself a stopwatch and train to guess when necessary, I know it's so hard at first especially if you are a bit like me but the point is you can't afford yourself leaving even a single unanswered question. And very importantly: avoid starting to write automatically, read carefully (not necessarily word by word, that's a matter of practice) that will save you time, and get a picture of the problem in your mind first!
I didn't want to have someone else tutoring my GMAT prep so I decided to start by getting familiar with the test, the scoring, type of questions... I first worked on learning what the GMAT was intended to test without worrying much about the time, this was particularly important for the Verb section since English is not my first language, so I had to relearn correct English.
For the Quant section I solved each of the problems on the GMAT Review 12th ed. without checking their solutions (I had to work on the simplifying thing and that is for sure not the main purpose of the proposed solutions in that book) so I'd say if you know the math feel free to skip the solutions section. That's just me. I thought it would be helpful to get a sort of a catalogue of all the types of GMAT problems. I couldn't find any so I decided to do tons and tons of problems until most of them started to be somehow familiar to me. I created my own notes along the way; I mean not a catalogue but a list of the topics I realized I was facing more often.
For the verbal section I did read each one of the explanations found in the GMAT Review 12th ed. that was my way of learning to think as the GMAT wanted me to think as for the SC, RC and CR. So, honestly don't get discouraged if you feel like there are always like 3 correct answers (to your understanding) for the sentence correction questions, (oh man!, that was me). Just let the GMAT teach you what correct English means for it. I also did many many exercises. For the SC I found it very useful to write a list: I would write on the left side the expression as I had thought it was correct (or rather the one my brain seemed to feel more comfortable with) and on the right side the correct expression.
Finally I did as many Tests as I was able to get for free (some of them are mere garbage); I learned from this community that Manhattan CATs are a bit tougher than the actual test so I thought that will be a good investment I think it was like 39 usd for 6 exams, did all of them simulating the real thing (Time, breaks...). The Quant Section is harder than the one in the actual GMAT, my Manhattan Q score was always around 48 (the real was 51). On the test day I felt like there was something wrong since the math seemed so easy towards the end of the Quant section, something that had never happened with the Manhattans. The verb also seemed less complicated in the real GMAT than in the Manhattan CATs.
Well, that's roughly my GMAT prep, just let me know if there's anything else I can do for you!