We frequently see questions asking about what study guides exist for this certification. This seems a large enough topic for a page all it's own - right here.
Words to live by:
Write your code as if the person who maintains it is a homicidal maniac who knows where you live.
The exam assessors aren't thinking like my-algorithm-is-bigger-than-yours code mavericks. They aren't looking for the next great breakthrough in record-locking. They aren't even looking for new, creative implementations. They are looking for development that says, "I'm a thoughtful programmer. I care about maintainability. Readability is very important to me. I want everyone to understand what's going on with the least amount of effort. I write careful, correct code. My code might not be the snappiest, and it might even incur an extra few bytes in order to make something less complex, but my logic is simple, my code and my design are clear and implement the specification perfectly, I didn't reinvent the wheel anywhere, and gosh, wouldn't you just love to have me on your team? If your project submission says all that about you, you're in great shape.
from: Sun Certified Programmer & Developer for Java 2: Study Guide (Exam 310-035), Third Edition
by Kathy Sierra and Bert Bates
Chapter 10 Understand the Sun Certified Java Developer Exam Process
McGraw Hill, Paperback, Published December 2002, 711 pages, ISBN 0072226846