Happily, what's going to be on the social work exam isn't a complete mystery. The ASWB publishes a spelling out what to expect in great, potentially anxiety-provoking detail. Take a look. And breathe. And skip over the little details--just focus on the headings. "Oh, wait," you may find yourself saying. "I know this stuff already."
The web is chock full of guidance about getting the KSAs learned, reviewed, or re-remembered. Here's a great place to start: The Pass the ASWB Exam blog has an section-by-section guide to the ASWB KSAs, grouped under the tag, "KSA of the Day." Links, study tips, etc.
It's content time. Get to it!