I have no idea where to start, and I want to study by myself. What should I do?
Short answer: Get the The Official Guide for GMAT Review and a good strategies book.
There are basically two parts to studying: understanding the test and practicing.
The best way to understand the test is to have somebody show you what the test is like, what to look out for, what to study, how the test works, etc. A good teacher with lots of experience teaching can help you do this. However, for various reasons, many students decide to study on their own. For many students, a good book is enough to help them understand the test. For these people, TestMagic offers the following advice.
Choosing a good book is really important. A good book will lead you very carefully through every step and show you the pitfalls of the test. A good book will not teach you things that will not be on the test. A good book will explain things in a way that is easy to understand and remember. In short, a good book should "feel" like a private coach, like somebody is talking to you. TestMagic is working on a book like this and you can see some parts of it on this web site.
The truth about most books on the market is that they are shooting for the "middle market--" people who don't need an 800 on the test, people who have slightly above average ability on the test and are looking to raise their scores 100 points or so, people who don't want to spend too much time studying, maybe a few weeks or so.
If you can only buy one book for the GMAT, TestMagic recommends the Kaplan book--it will give you a good introduction to the GMAT and the software is pretty good, better than the software in the Princeton Review book.
The next part of test prep is practicing. This part is extremely important--you need to get used to taking the test under real test conditions. Sometimes you might find that there is some part of the test that you do not know about or some other strange thing that you have not seen before, for example, the combination of a hard word and a complex grammatical structure might result in an unanswerable question. You need to know this! The only way to practice is to use official materials--no company can produce questions like those that ETS produces. Believe TestMagic--it is extremely difficult to make good test questions. Why? Because ETS spends millions of dollars on making their test questions perfect. Believe us--we make test questions also and it is extremely difficult to make questions just like those on the real GMAT. In short, the best practice materials are those released by ETS.
However, there is one drawback to the questions released by ETS. When ETS releases the questions, that means that they can almost never use those questions again. That means that you will almost never see those questions again. Part of the reason for this is that ETS evolves. One year they use certain kinds of questions or topics, the next year they do not. So, if you use ETS materials that are more than one or two years old, you might very well get an outdated idea of what your test will be like.
I have done all the math questions in all the books and they are too easy. Where can I get harder math questions?
Short answer: Kaplan.
Bad news, folks. We have looked all over the place for the hard problems that you will get on the GMAT if you are scoring high on the test. We have checked all the books, including the ones that are specifically for the math sections of the GMAT and GRE. No dice. Many of our students can get 800s on the math sections and say the same thing--most of the problems in the practice books are just too easy. However, many students find that Kaplan offers the hardest math questions, and they feel satisfied using their products, especially the CD-ROM.
Our advice? Try various math books and do the hardest questions in all the books. You might want to try some older GMAT books, too, if you can find them.