I've CLEP'ed Intro to Psychology and Human Growth and Dev, but not Sociology. A good study guide is instantcert.com. They have fill in the blank question lists that work really well. You have to pay 20 bucks to get in, but I think it's worth it. Just remember to cancel afterwards if you don't want to keep the subscription. REA CLEP study books are supposed to be good too if you'd rather just get a book. Textbooks tend to have a ton of stuff in them that you don't really need for the CLEP. The CLEP study guides are more specialized and focused.
CLEP's are all multiple choice, and they don't penalize for wrong answers so answer EVERY question! Also, make sure your school accepts it too. I took College Mathematics CLEP only to find out that my school didn't accept it, even though it was on their list of "accepted CLEP's." So it'd probably be a good idea to double check that.