It's true: the percentage right/wrong has little bearing on your score. You could be getting every other question wrong towards the end of the test and still be breaking 700. Of course generally, the higher percent you get right, the better your score, but it's not that simple, and there's really no way to make a prediction. Also, you only mentioned verbal - if you get a 51 in math, your verbal score doesn't need to be spectacular to break 700 total.

That said, to score above 700, you should probably be getting virtually every easy and medium level difficulty question right. You can gauge difficulty by the order in which problems arise in the OG - the earlier problems are easier. As for the harder questions, I'd say you should also be getting 50-75% of them right.

Good luck!