Hi Shyam ,

First of all you should collect all the materials which you need for your preparations.This should include texts which you are planning to refer,notes and most importantly previous year question papers with answers.

Secondly make timetable so that you can complete the portions within the time provided. Just roughly refer the previous year question papers so as to get an idea about the pattern of questions .

Now it's time to study. You should understand each and every topic and also maintain your own views about  the same.

It is subject in which the examiner evaluates you on length but you should have a very good time management. Also keep in mind that examiner is not going to read all your answers.Underline important points,make flow charts etc.

Hope this helps.