Just need above a 500 GMAT Score

Like you said it is very important that you pace yourself in the GMAT to complete all the questions in the prescribed time,The GMAT will heavily penalize you for unanswered questions.So I assume that you must have left a few questions answered in your previous attempt and that's the only reason you ended up scoring 450.

You should start practicing on timing yourself.Start with taking a set(usually 25 questions) of CR,SC,DS & PS daily and ensure that you time yourself.When you are done with the test analyze the solutions and try to identify your weak spots and work on them.Typically a math problem requires 2 min and a verbal problem requires 1 min 45 sec.Do this until you are very sure that you can complete all the questions in the allotted time.After you feel that you are good at timing start taking practice tests.

I am sure your next GMAT attempt will be a fruitful one and you will come out with flying colors....All the best..

Thank you very much for you input!! and good luck on your 750

I might be partial, but there's no harm in taking a prep class. It sounds like your GMAT score is very important as it will determine the position you get in the Air Force. If you have the time to devote to it, a prep class will virtually guarantee that you break 500.

That said, some people are fine studying on their own. You should buy the GMAT Official Guide (a big orange book) to practice, and try the free practice GMATs from mba.com. Most people tend to do roughly the same on the real test as on the GMAT Prep tests, so those will give you a pretty good idea about where you stand.

Good luck!

Call me an idiot, but I went through the entire Manhattan GMAT course with all the books and online lectures, did 80% of the basic problems, and scored 490 on the actual test.

Prep courses don't guarantee anything.