It’s not really realistic to increase your SAT score through learning vocabulary words if you have less than 12 months to prepare for the exam. There are thousands of words that you would need to learn and know their definition to increase your score going that route. There are about 20 vocabulary related questions on the entire test so is it really cost effective for you to memorialize or learn thousands of vocabulary words in a 12 month span.
You can more effectively use your time concentrating on other section of the SAT. If now, for example, if you are in the sixth grade and are already thinking about taking the SAT then by all means, learn your vocabulary words and increase your reading comprehension skill.