SAT writing MC?

<p>I swear my writing score just wont go up. :( I am using the Maximize Your Writing Score On the SAT book. My friend recommends me to read this book 2-3 more times. Does anyone have experience with this book? My score is around >600 and it wont go any higher. Is practice really enough? There are some questions where I'm just like, " Nope. Don't know."</p>