Yeah, it's ok to use books outside of your course. I've heard that one is pretty good, and have also seen excellent reviews of Analytical Workout - I believe that one is from Princeton Review.
This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.
Messages - keating
Have you already registered and paid for the course? If not, I would strongly suggest Princeton Review instead. Their methods are far superior, and so is their guarantee (no fees whatsoever to retake a course). You also don't have to go to their center to do practice tests and exercises - you take it all home with you.
If you stick with Kaplan, just focus on getting all your homework done and asking for help if you need it. Make sure you get what you need and work hard, and you should do ok.