How can I improve my SAT score?

Get Gruber's Complete SAT Guide off Amazon - the used copies can be REALLY cheap. It is an excellent tool for the SAT math section (though not so much for the reading/writing sections). The first time I took the SAT, I scored a 700 on the math section, but I retook it and scored a perfect 800. Even though I would also attribute taking more high school math classes as a factor to my success, I would say that most of it came from the Gruber's book (even though I didn't even use it that much). Do the diagnostic test at the beginning and identify your weak points - then go through to the specific sections and do all the problems. That should definitely help your score.

Also, for reading, it is important to know that all the answers to the questions for the reading passages will be contained in the text. There are no hidden meanings - everything you need will be explicitly stated, so you don't have to overthink or overanalyze things. My reading score also jumped from a 690 to a 760 when I used this strategy.