Use veritas prep
for your preparation the next time you take the exam. I improved my score from 560 to 660.
I have my books (15 in total) for sale for about 300 dollars. There are about 9 quantitative books and 6 verbal books that cover every area of the GMAT with discussions on the fastest way to solve the problems. Reach me at 281-687-7714 if you are interested.