While I did pass, I do *not* recommend my study methods to anyone.
I passed my SCJP last year and in a fit of unbridled optimism purchased a voucher for the SCWCD a few days after passing. I made a few half-hearted attempts at studying for it, but skated along until I realize at the beginning of July that my voucher would expire by the end of the month! On the 7th, I scheduled my test for the 31st and started cramming, but due to family and work commitments really only got about 24 total hours of studying between scheduling the exam and taking it today at 13:00.
Resources I found useful:
1. "Head First Servlets and JSP" 2. "How Tomcat Works" (Budi Kurniawan and Paul Deck) 3. Frederic Esnault's SCWCD Study notes
Based on my experience, I'm not really sure I would purchase another "Head First" book -- maybe this type of learning works well for some people, but the "fun" fonts, graphics and layouts just distracted me from the content.