Just thought i'd share my experience. I got a 740 in GMAT (51 in quant & 39 in verbal) after 2 months of studying for it.
I don't believe that GMAT is a very tough exam and i think tht attitude helped me in a big way. I was always relaxed while solving questions and mindful of the strategies i had devised.
Let me first tell u about the resources that i had to work with-
1. Official Guide (11th edition)
2. Lots of notes courtesy gmatclub.com
2006 cd which i got from somewhere.
The official guide gives u a very good idea about the kind of questions that come in gmat and is a must solve for everyone. However, in my experience, the questions in O.G. are not of the highest difficulty level and if you're aiming for a score of above 700, maybe you should look for some other reference book. For quant, its probably a good idea to solve problems of a couple of difficulty levels higher than the O.G. This helps you tackle the really tough questions that you get when you're heading for a quant score of 50. During my gmat, the questions i was getting around the end were really really tough. Something that could help you that is this book by a Prof.Arun Sharma by Tata McGraw Hill publications called quantitative aptitude for CAT.Its for the indian MBA exams but if you go through that book, a good quant score is guaranteed.
About verbal...39 isn't much to speak about...I was getting higher scores in practice tests but i got pretty exhausted during the actual test. I guess i should've practiced a lot more. In any case, i'm hoping someone with a good verbal score has something to share with everyone about that.
Some strategies i'd recommend :
1. Keep track of time. Divide the allotted time in 10 min slots n decide which question should u be at wht time. If u're ahead of that question,slow down.If not,speed up. Keep 2 mins in each section in hand while slotting the questions for the end.
2.Use the options. Quickly write down 1 2 3 4 5 on the rough sheet and eliminate as soon as u read the options. Especially important in data sufficiency, CR and SC.
3.Don't panic. You have enough time.
4.Use each ten min break to drink plenty of water and maybe something with sugar like a chocolate. Before you sit for a section,close your eyes and take a few deep breaths.
All the best