You gotta read books; you gotta write some code. Give yourself 3 months (less if you're a C++ programmer).
Get some examples from the CodeBarn, and stories at the Campfire.
The SCJP exam is now for Java2 (Java language version 1.2), but you can still take the 1.1 exam. The Java2 certification is almost identical to the Java 1.1 exam, but adds two new objectives: Collections and GridBagLayout.
You'll take it at an authorized examination center. They will have security to make sure you don't take anything in, or out, and that you are the registered person (can't send a Java Guru in to take it for you).
About 2 hours, 60 questions. There's plenty of time, but the questions are HARD. Shockingly hard.
But not so bad if you do steps 1 and 2 and 4.
How do you know if you're ready?
You've been studying hard for at least 8 weeks (much more if you're also new to programming and especially object-oriented programming).
You've been writing lots of code and trying things
You're getting 100% on Rule Roundup (and the cows aren't distracting you any more...)
You're getting at LEAST 90% on both the Roberts & Heller sample questions and the sample questions in the Boone Certification book. Visit our Readin' at the Ranch page...