Full-length practice tests are generally best. Lots here: www.socialworktestprep.com. Also on the site, a free study guide, free practice test. Good luck to all to-be-licensed social workers!
Don't! Most of the learning you'll do in school (and for the exam) will likely come from internships. If you want--just for fun--to see what the exam looks like, take a look at the sample exams linked here.