I have already covered some of the following in my
debrief.
I assume you haven't done any mock tests yet. My immediate advice would be to do one pretty soon, regardless of whether you feel prepared or not. The big reason for this is that you need to figure out which parts of the exam are difficult for you, so you know what you need to practice most. Your weaker areas will likely have the most possibilities for you to improve, giving you easy access to some extra points on the exam.
Once you've found out which areas are tough, I would suggest you try to do the Manhattan sections of those areas and then practice solving those types of questions using the GMATclub question bank. While doing this, it's good practice to carefully read the expert solutions, so as to pick up more tips on how to find the solution faster.
While the OG has next to nothing to offer in terms of strategy or explanations, what it does have is an easy way of doing many questions in rapid succession. For this reason, it is a useful resource when you have learned some strategies and you want to practice solving many questions in a row without knowing what kinds of questions will come up next, similar to the way you'll be doing it on the exam. On the exam, you will have to be very comfortable with solving ~30 questions in a row without losing focus, while maintaining a steady pace. Using the OG in this way can help you get used to that.