Hi Ameya,
Congratulations on starting your GMAT journey! The MGMAT books will definitely be enough to get you started, but you'll also definitely need some version of the Official Guide, and you'll need to take CATs regularly. (No need to take "full" ones with IR & essay every time, though).
Here's what you should do:
1. Take a timed practice test. You've already done this step!
2. Analyze the practice test you've taken in a lot of depth. Which areas were you weakest? Strongest? Fastest? Slowest? Decide which topics and question types need more of your time and attention. Be very aware of timing issues as well.
3. Study topic-by-topic, going chapter by chapter in the Mprep guides, then practice each topic with OG problems. For example, read the chapter on SC subject/verb agreement, then go do a set of 8-10 problems in the OGs that relate to that subject. You can find problems by topic using GMAT Navigator:
https://www.manhattanprep.com/gmat/stor ... navigator/
Do this for each chapter in the Quant and Verbal strategy guides. Aim to do this in 8-10 weeks.
4. Make sure you are tracking all of the OG questions you do, and timing yourself while you practice. Hold yourself to strict 2-min time limits per question! (I highly recommend using Navigator to track your OG problems)
5. Alternate between Quant and Verbal. Don't just focus all on quant! A lot of students make this mistake. You can't get a top score by only focusing on quant. You might think your quant score from the 1st CAT is lower based on percentiles, but this is probably a misinterpretation:
https://www.manhattanprep.com/gmat/blog ... mat-score/
6. Keep a detailed record of the mistakes you make in addition to just tracking right and wrong answers, so you can locate patterns in your errors:
https://www.manhattangmat.com/blog/index ... -studying/
7. Take a practice test after 3 weeks, then 2 weeks after that. Increase to a test every week for the last 2 weeks before your real exam.
8. Practice your skills with random timed sets out of the OGs once you've covered all of the content in the strategy guides . Set the timer for 20 minutes, for example, and do questions 1-10. The OG problems generally get harder as the question # increases (within a given question type), so questions 1-10 will be easier on average than 101-110. Start in the middle of the section if you want more challenging questions.
9. Analyze your data from the random sets and practice tests, and go back to any topics that need extra work.
10. Take GMATPrep CATs. Download the software from mba.com and take these tests as the last few before the real test. They won't have answer explanations or metrics, so we recommend using Mprep CATs for most of your study time, and saving these for last. (They're less helpful for analysis, but arguably most predictive of your real score, since they're written by the actual test-makers).
Good luck!