I have sent emails to friends about how I went about preparing for my GMAT. This was very effective for me (I ended up with a 760) and I thought that sharing it more broadly might help others. Below is a summary of what I did.

Sections:
Quantitative
Verbal
Essays.

Quantitative:
Not very tough. High school math. Need to brush up some formulas, and practice a bit to rule out silly mistakes.

Verbal: This was the tough section for me. Practice helped a lot in this section.

I found Sentence correction to be the trickiest part. I spent a lot of time understanding the typical sentence correction cases given on the GMAT. Primary References: Kaplan GMAT, Princeton GMAT, Spidey’s notes (this
one is a pdf file
http://www.sentencecorrection.com/forums/index.php?s=f9fe5dd7b308d3a5a03c21857f941258&act=attach&type=post&id=8)
Spidey’s notes is amazing, but you need to read the chapters from the books to really understand what is mentioned there.

Reading Comprehension..Is not tough, but requires a bit of practice.

Logical Reasoning..again refered to Kaplan GMAT and Princeton GMAT chapter summaries. Then it was getting some practice questions done.

For practice I used these:

  • Few questions in Kaplan and Princeton.
  • GMAT official guide, 11th edition. This book is awesome. It is by the people who conduct GMAT and has real past GMAT questions. This alone is sufficient for practice. However it has no notes, hence the other books are required.
  • GMAT Powerprep .. The best and most accurate test and is given free when you register for the GMAT. It has 2 tests. Best to take them in the last week. I practiced tests from Kaplan as well…but these are way tougher than the actual GMAT.

Regular 1 hours each day, for about 5-7 weeks is more than sufficient for the GMAT.