Unfortunately, you do not have much time to get an improvement but you can get a better score than yoru 590 in a week. I would suggest you focus on technique over knowledge - learning from questions as you go.
Remember to focus on each question as it comes and make a quick decision about whether you are going to do the question or not - I don't know if you ran out of time but it is important to finish all of the questions, do not leave questions at the end, it is better to skip questions in the middle.
In verbal I would recommend answering the questions in RC and CR in your own words before looking at the answer choices - the answer choices can be misleading and get you to look at the wrong things. You should know what the answer should be before you look at the answers.
In sentence Correction you should not try to edit the sentence but instead focus on one error at a time - if you find a problem in the sentence go through each of the other answer choices eliminating answers that copy the same error.
In Math, look at whether you had a harder time with Data Sufficiency or Problem Solving - one quick area to increase is in Data Sufficiency strategy - having a consistent way to approach the logic behind DS can help increase accuracy.
That said, you should take at least one more practice test before Saturday and most importantly enter the test with a positive attitude, you can do well on this test with just a few tweaks.
Best of Luck
Becky
Master GMAT Instructor
The Princeton Review
Irvine, CA
