Read all the sticky's.

After that, I can help you with more specific questions.

If you're trying to jump from a 540 to a 720 in two months, it will be tremendously difficult. I went from a 640 (diagnostic) to a 730 (actual gmat) and it took me 7 weeks of hardcore preparation after about 2 months of very loose preparation.

I would recommend you do 10 questions at a time, and time it. Try doing the first 1/3 of each section on the OG. If you cannot finish these questions quickly, you will have a difficult time scoring 700+. A 700+ should be able to breeze through the first 2/3 of each section.

You need to identify what you are weak at. For example, problem solving is not a good enough answer. It has to be geometry, or arithmetic or probability etc.

For the verbal, you need to work on each section separately. You need to learn every rule in sentence correction and use a quick methodical checklist to eliminate incorrect answers. For reading comp, start reading intellectual periodicals, daily. Critical Reasoning is a bit tougher to learn, but you just have to recognize the pattern of arguments that come up over and over on the GMAT. Identify the conclusion and manipulate the assumption to get the answer that the question is asking for.

If you want a 700+ you will need to dedicate more time and get serious with the test. From afar, the GMAT looks pretty easy, but in actuality it is more difficult than people think it is.

Yes, but not my idea. It is the idea of a fellow gmatclubber. I got a postcard from Time magazine for an annual subscription for $20. It was like fate knocking on my door. I subscribed and read it cover to cover every week. It was boring as heck, but I just had to do it.