The SAT Reading section contains some very difficult and easily confused words. Knowing the hard and fast definitions of as many words as you can is very useful in not getting tripped up on the Reading section.
If you want to do well on the SAT Reading section, you’re simply going to have to build up and strengthen your vocabulary. There are many good sources of suggested study lists to consult, and flash cards may help. But learning new words (and refreshing yourself on ones you half-know) is a long-term process, so start learning words as far before the test as you can.
SAT Prep Plan: SAT Tips 
