exam technique for P3

Seriously, I am too much worried about it that what exam technique should be adopted for specifically for P3. I mean how it should be prepared at which level that me feel some confidence. What will be the best way for answering the exam question.
Theory or model description is enough or application of it also must?
you have provided exam techniques for some papers like F8, P1 and P2 but not P3 why? If it is available then give me direct link for it . I have searched but i could not found it

Please help me as soon as possible. I shall be very thankful to you for this favour.