Hi!!! if you want to score a good marks in scjp exam ill tell you the secret what eaxactly you should do.I got 100% in the exam so here is a way to help you.Hope you find it useful:
1.Read the book Kathy Sierra Scjp 310-055 for SCJP at least two times
first time when you read try to understand as much as possible coz it might be useful for your carrier in the near future.During your readin also mark the points which you feel important.
Next time you read you read the important marked points at mark them with a book marker for future referral.

2. Now go on the net solve all the available questions.Donnt worry it might put you rmoral down but as you keep on doing the exercises youll be confident to solve the questions on your own and also you'll develop a clear picture of what kind of question comes and how to look at it to solve it.
here is one question for you which you won't find anywhere else:-

public class Donkey2 {
public static void main (String arh[]){
boolean assertzOn = true;
assert(assertzOn):assertzOn= true;
System.out.println("assert is on");

What will be the output of the above code if it is run twice once assertion disabled and the next time enabling the assertion?

And the correct answer is
assert is on
assert is on

This will be enought for your SCJP test.SO BEST OF LUCK AND START PREPARING :)...