Actually, a friend of mine was planning on giving GMAT and i tagged along.
I used
OG 13, GMATPrep Software (gave both the tests 3 times), Aristotle SC Grail (3 days), Chili Hot GMAT Math (1.5 days), Manhattan Number Properties and Word Problems guide, Manhattan Test Series, All Free Online Tests (Manhattan, Kaplan, 800score, Princeton and a few others). GMATPrep software has additional questions apart from the test.
I started with diagnostic test in
OG and found that i as really bad at verbal and above average at Quant. Accuracy in all sections of verbal was less than 50 and abysmally low at 25% in SC. In Quant, i could never get probability, inequality and combinatorics problems right initially.
Initial 2 weeks i was reading around aimlessly without much improvement. Then as recommended by lots of members on the forum, i gave the tests but focused more on reviewing the questions, whether right or wrong. That, i think, is the key to not repeating the same mistakes.
As you can ultimately see that i didn't do as good on verbal, but overall score came out ok.