If you're scoring in the 300s, there are some fundamental issues with your math and verbal skills. My advice is to take a step back and review your basic math and basic grammatical rules. Head out to the library or bookstore and get yourself a couple basic math and English textbooks or workbooks. Nothing GMAT related - just foundational knowledge.

THEN, once you're comfortable with that, you need to practice applying what you learned to actual GMAT problems. This is the hard part, but worry about that after you've attained the foundational knowledge.

That large of an improvement is rare in such a short time, but I have seen it. You'll just need to put in a lot of work over the next couple weeks and give it a go.

Good luck!

Actually, I also need at least a 450 also to get into a state university here in MA. I haven't taken any practice tests yet, but my official test date is Dec 13. My studies are progressing fine, right now I'm going through the OG books, and they are very helpful for reviewing, as everyone says. My initial goal was to get a 700+, though I'm not counting on it. I want to do my best obviously, but I'll be pleased with getting 600+.

I am not sure what happened. I have been out of school only a couple of years. I have taken math courses through calculus and discrete mathematics for computer science. I earned a B or better in all math classes. I guess I will try the practice test one more time (after my light preparation). If I get at least 450 or better than I will try the "real" thing. If not, I guess I will have to apply the following term.

As you've probably noticed, the GMAT doesn't test calculus, or even precalculus and trig. In fact, you probably learned the highest math needed for most GMAT questions in middle school. One problem a lot of engineers have is that they are great at advanced math but forget more fundamental topics. Dig out your old Algebra textbook and get studying!