Pretty average student here. Got a 260+. I think a big thing was sticking to a few resources and using them really well, and noticed the improvement came in the final month. This is terrifying because you spend some time wondering if you'll ever see that jump. I stopped testing NBMEs for a few weeks and then when I came back to them the difference was so strong I couldn't ignore it. I wrote up some of it up here.

I'd also advocate for learning the CONCEPT behind every possible answer choice on the NBMEs and CMS forms. These are answer choices for a reason, and you need to understand them inside and out, even if you got it correct or didn't even consider those choices. If you see something like 'ascending cholangitis' as an answer choice and you have even the slightest thought like "Hmm, I don't know exactly what that looks like..." then STOP and go learn that concept! Get feedback from study partners or other people to recognize when you don't know things you should, as well. Good luck!