I'm not trying to be funny here.........but a GREAT book to help you prepare and pass the salesperson exam is "Real Estate License Exam for Dummies". I don't have a super long attention span when it comes to books - when my friend let me borrow the Illinois Salesperson prep textbook, I got through the first chapter before I was bored. I bought the "Dummies" series book in addition to help me understand some of the more confusing topics. It does an AWESOME job of explaining everything to you in simple, easy to understand terms. It's worth the $15-20 buck investment.
The test itself wasn't very hard, in my opinion. For the Illinois test at least, you do have to have a pretty firm grasp on the specificities of some of the topics however. Some of the multiple choice options they give you could ALL be construed as correct, but they want the BEST answer. It's not super easy to use process of elimination. It's a computerized test you will most likely take at a proxy location near your home.
Hope that helps!