Hey Sneha,
First off, good job! A 620 is a good score. So don't be sad about it. But yes, there is definitely more room for improvement. Not attempting a question can sabotage your score a lot worse than getting a question wrong. So for the next time, I suggest you just select some answer instead of leaving it blank before you start working on a problem and then change it to match your answer accordingly. This way, GMAC will recognize whatever answer you chose as the final answer even if your time were to expire. I think pacing is also very important. Maybe you can download Walker's
GMAT Timer and use it with your studies.
At this point, you're aiming for a 700+ from a 600+ range. So I suggest going through the
GMAT Strategies for the Advanced thread.
You already have the
MGMAT SC, so make better use of that and concentrate well on the topics analyzed and make sure you go through it thoroughly. Powerscore CR is a good book for CR too. As for RC, try deconstructing the passage into four main parts:
1. Main Idea
2. Structure - (First para: Second Para: Etc)
3. Purpose - Why are they talking about this here? Like, an explanation of a new test for cancer would help thousands of people in early detection. This is usually in the last paragraph.
4. Perspective - Is the author agreeing with the statement presented in the intro? Is he contradicting it? What is the flow of the passage like?
This will help you narrow down answer choices.
With Quant, I suggest that you go through the
MGMAT books again to get a good grasp of the concepts and then try the
GMAT Club tests for greater accuracy. I also recommend not trying to solve each problem. If you can plug numbers, do it. I know a lot of people who get bogged down with time constraints because they want to get a physical solution to the problem. The GMAT isn't testing you on your math prowess and the computer doesn't know if you manually solved it for 5 minutes or plugged a number in, in 5 seconds. So if you can save time doing that, do it. Check out the
Math Book on GMAT Club for more ideas. Solve a problem or two from the forums daily. Just keep in touch regularly.
Take a day or two off. Maybe a week. Relax, clear your mind and start afresh. Here are some other links to help you out.
1.
Critical Reading Methods2.
Critical Reading Notes and Shortcuts 3.
Critical Reasoning for Beginners4.
Reading Comprehension Guide5.
Math Books for GMATThere's a whole load of information on these threads that you can use to your benefit. Consider using an
error log so you can estimate what your weak areas are and work on it.
Hope this helps!