after basics

If you are done with princeton review book and basic grammer (Wren and Wartin) then go for few sample tests. Sample tests are available with the princeton review book and Kaplan. Don't take all the sample tests at this. 2-3 sample tests would be enough. Also the sectional sample tests are available at topscore.com . Around 25 sample tests are available at this site. Try to complete them at this stage. Once you are through with the sample tests, move to adavnce topics. Some of advance topics from quatative and verbal are available in kaplan review and kaplan verbal. These two books contains good material for advanced topics. Also at same time start reading Arco essay book for gmat essays. Though this book may not be the best but this is more than enough to prepare for gmat essays. Don't skip first two chapters from Arco book. These chapters provides detail about the essays basic. We must understand essay is not just about writing the words, But gmat judges your ability to express clear ideas through essays. You analytical and decision making abilities are judged through essays. So its very important to through the first chapter in arco essay book. This chapter contain some "do and don't" list. Which we should remember while writing the essays. Ideally you should spend approximately two weeks time to finish both the kaplan book and the essay book.