A sure way to succeed on the SAT reading test: Read! It sounds obvious, but since the passages range in difficulty, your best bet is to read on your own often. Don't rely simply on the reading your classes require you to do. Read more of what you like. If you are a sports fan, read the sports page of the newspaper or biographies of your favorite players. If you are into science, there are plenty of science magazines describing cool new developments. If you enjoy fiction, try reading more of an author you enjoyed.
The vocabulary and sentence structure we encounter in reading is more complex and sophisticated than what we encounter in talking and texting, so exposing yourself to some reading every day is a great way to increase your chances of success on the SAT reading portion.
Also, try keeping a notebook or online journal of new words that you encounter while reading. This can become your own personalized vocabulary list.