last month I passed the SCWCD exam with 68%. Although this is not a high score I'm very happy about it because I expected to fail actually (it was the last week before voucher expiration and I had not much time to learn).
My tips for preperation:
Buy HFSJ and get the errate file from oreilly.com (I think it's time for a second edition of HFSJ - it tooks hours to work through the errata ).
Read HFSJ more than once - make your own notes, build example applications.
Get the specs and print them out. If you want an excellent score read them also For my part I didn't read this 300 page monster documents.
If you have the chance to get the Desmond book: get it! It contains a nice 'Last Minute' part.
Both HFSJ and Desmond contains mock/test questions. I think it's a good idea to use them as a test for yourself. But for my part I only use them as a training unit: I go through it, meditate about the questions and read the solutions. The advantage is that some explanations get it to the point.
In the exam there are questions from all topics. Some of them are very tricky. The best advice I can give you: know your Deployment Descriptor! You should know the syntax and location of all elements mentioned in the books.