The first thing you should decide is how you want to prepare - classroom setting, self, or one-on-one setting.
If you're going to prepare without any help from tutor, you should begin by taking a diagnostic test. Taking GMAT Prep would be a good idea. You will be able to figure out the concepts on which you need to improve.
Books: You'll find that a whole bookset - Mahattan, VeritasPrep, Kaplan - will be good enough to prepare. I personally found VeritasPrep best. I found Manhattan bit too simple. I'm going to list down a couple of books topic-wise.
Sentence Correction :
Manhattan Prep (5th edition)
Critical Reasoning : Veritas Prep
Reading Comprehension : Manhattan/Veritas
Advanced Verbal Strategies : Veritas Prep (This book was extremely helpful in pushing my score beyond 40)
Quantitative : Veritas, Manhattan, and Kaplan are equally good.
Manhattan books are flooded with strategies and shortcuts.
Veritas Prep books focus on just the things that matter on the exam. They have very intelligently edited their books.
If you're short on time, buy Veritas Prep for quant. They can be finished a lot quicker than Manhattan/Kaplan books with just as much knowledge (if not more).
Sites: GMATclub,
Magoosh, and Manhattan forums are quite resourceful. The forums are full of 700+ level questions and pretty decent explanations. You will be surprised how much you can learn from such forums.
I hope this will be helpful!