Hi Mary,
Given that you only prepped for about a month, it’s not surprising that you did not achieve your 650+ GMAT score goal. Remember, because of the vast amount of information tested on the GMAT in so few questions (37 quant questions and 41 verbal), you need to give yourself ample time to fully learn the concepts/topics that may be tested on any given GMAT. Thus, when prepping, you want to strive for linear and targeted learning, and follow that with focused practice. In other words, you want to master one topic before you move to the next. Once you have a deeper understanding of both quant and verbal topics, you will be able to more efficiently attack any GMAT question, and thus you will see an improvement in your timing.
So, when studying verbal, learn one topic at a time. When learning about Critical Reasoning, for example, you want to learn about all aspects of Critical Reasoning: strengthen and weaken the conclusion, resolve the paradox, find the conclusion, must be true, etc. Follow up your learning with focused Critical Reasoning practice, so you can determine your specific weaknesses within that topic. You should do the same for Sentence Correction and Reading Comprehension.
Follow a similar routine for quant. If you are learning about Number Properties, you should learn everything possible about that topic: LCM, GCF, units digit patterns, divisibility, remainders, etc. After that, be sure to practice with a lot of questions (50 or more) just on Number Properties. Doing such thorough practice will hone your ability to apply what you have learned to realistic GMAT practice questions.
Once you feel you have improved your GMAT skills, put those skills to the test by taking some practice exams from MBA.com. You might also find it useful to read this article I wrote that contains advice on
how to improve your accuracy on the GMATPlease keep me updated with your prep and feel free to reach out to me directly if you have any further questions.
Good luck!