To start your preparation for the GMAT test I recommend that you do three things:
1. Buy GMAT Review ~ The Official Guide (ISBN 978-1119507673). The Official Guide or OG has all the background information you need, as well as a Diagnostic Test, a Math(s) Review, and a section full of sample questions for each area of the test. If you have not yet done the Diagnostic Test when we start studying, I might suggest that we spend at least some time looking through it to highlight your strengths and weaknesses. I also highly recommend my own book (well I would, wouldn’t I?) The Ultimate GMAT Quant Guide Part One, available on ibooks for iPad, although be warned that it’s a little out of date as it links with a previous version of the Official Guide. I’m currently developing further online GMAT prep materials so watch this space!
2. Download the free GMAT test-preparation software from mba.com. You may want to do one of the practice tests early on to get an idea of your current level, and the second shortly before your actual test, both to see how much you’ve improved and to give you an idea of what the real thing will be like if you’ve never done it before.
3. Have a look at the Resources tab; I’ve compiled a list of useful resources which you might like to investigate. Alternatively, just ask.
You’re now ready to go. You should practise regularly on your own, keeping a record of the questions you found difficult or answered incorrectly and any silly mistakes you made. Make sure you are familiar with the test format and timings: you can be penalised quite heavily for not completing the test. The time does go quickly, but if you’re well prepared you can enter the exam with confidence.