To improve your verbal scores, you must do one thing. READ!
I can personally attest to the truth of the above. I am an international student and I took the SAT in 1999 and scored 680 on the verbal portion. I was denied a visa by the US embassy in my country, and I didn't try to come to the US for another 4 years. In that time I read a lot. I wasn't reading to improve my test scores; I had met someone who inspired me to. My father had lots of books - kind of his personal library - and I would start from one end of the shelf and read through to the other end. I don't know how many books I read, but they must have been in the hundreds. It really helped. When I took the SAT the second time, I got 800 on the verbal. I got 790 on the GRE verbal, 98 on the PCAT verbal, and 99 on the reading comprehension portion. Although, interestingly enough, I got 10 on my MCAT verbal...
That's my story. You probably don't have 4 years, but read anyway.