I took SCJP exam today and My score is 91. I think if you do not want to waste your time and menoy, you should buy a K&B book and do every self-test again and again utill you know why this answer is correct and other answer are wrong. By the way ,you can play "JavaRanch Rule Round-up Game" http://www.javaranch.com/game/game2.jsp.
It is easy to detect your weakness.
1. "Complete Java2 Certification guide(4th edition)" is a little out of date.
is too difficult unless you have enough time and want to get very high score.
is helpful and difficult level is almost same as easy questions in SCJP exam . I just did 100-question and have not do 400-question.