The best way to improve your GMAT scores is to prep hard for the exam over the course of about 6 weeks. Actually taking a class from a test prep company is expensive but worthwhile: if you have the cash on hand, then I highly recommend it. For the rest of you:
1) Quantitative is where the biggest bang for your studying buck can be found. Memorize your geometry formulas. Learn how to work with proportions and ratios, they are you key to about 40% of your word problems. Understnad your work and distance questions: you will see at least 2 on the exam.
2) Get really comfortable with your data sufficiency question types. These are actually easier than you problem solving questions, but people don’t really understand what the question is asking and often get them wrong because of it. Here is where 1 hour of studying and familiarizing yourself with the problems can translate into an easy 30 point increase.
3) Practice diagramming sentences for your sentence correction questions. 80% of your errors will be in verb tense, subject-verb agreement, pronouns, misplaced modifiers and passive voice/unnecessary gerunds. No what to look for so you don’t go to the test blind!
4) Buy a book I recommend “Cracking the GMAT” This will give you somewhere to start learning your strategies and is well worth the $20 or so.
5) The GMAT is a Computer Adaptive Test. This means that, the more questions you get right, the harder the questions will become. This, in turn, means that the better you are doing, the more you will think you are messing everything up. On test day, don’t be an amateur who gets flustered and thinks they are bombing. If you’re flustered, it means you are doing better than you could ever dream!
6) Take all breaks offered and get new scratch paper at each break.
7) Remember, the business school you apply to will get full transcripts of your essays. They don’t have to be great, but don’t write anything ridiculous that you don’t want your admissions committee to see.
8) Always remember that you are not looking for the right answer to choose in the answer choices, you are looking for wrong answers to eliminate!
9) Take notes constantly, especially during reading comprehension passages. This will stop you from “spacing out,” which causes untold amounts of lost points and heartache.
10) Always map out your critical reading arguments – Conclusion! Evidence! Assumptions!
Business school admissions are extremely tough this year and you need to do as well on your GMATs as humanly possible to be a viable candidate. That having been said, plan to prep hard, take it once and move on with your life!