The high percentile in verbal is due to the fact that people generally tend to score low in verbal. You may see lot of examples with 50Q, but will rarely see a 50V.
With a increase of approx 2-3 points in either of the subjects, you would be able to score 740-750. As you said you think you are good at Quant, then scoring a 50 in quant should not be very difficult.
Since this was your 1st test, I would suggest to prepare an error log
of correct and incorrect answers (you may include guess work as well). Now try to sub-categorize each question. E.g. from SC, it could be related to idioms, subject verb agreement etc. At the end you'll have a rough idea of your top 3 weak areas. The weak area could be a verbal or quant topics, time management etc.
Now focus on your weak areas and attempt GMAT Prep tests again and again. Don't forget to attempt the each GMAT Preptest atleast 3 times (i.e. total 6 test).
Between, remember both the subjects are equally important, so don't ignore either of these.
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