Institute's modules are good to make the concepts clear. For practice; you should solve compilation of last 15 years.
But first of all; create interest in the subject for which you have to imagine yourself as owner of one factory making investment of Rs.50 crores (what an idea sir ji).
The importance of cost accounting lies in the fact that if your cost of production is more than your competitors; your goods would not be sold and you will lose your market share.
For other tips; see my article REASONS OF POOR MARKS SCORED IN CA EXAMS published recently.
Also read cost accounting standards carefully and apply them while giving answers to your questions. I mean wherever possible, include their reference in your answer.
CA students are required to give their own opinion on the Financial Statement after qualifying exams (Practising CA). So read the subject first of all; analytically. Don't just read. Read for its application.
Now can you say why we should read Cost Accountancy ?
All CA Final students try to read the best available book but still very few get success because they get poor marks in Cost Accountancy. Why ? The read the materials without developing their skills in the subject.
Can you say what is the importance of Standard Costing ? Who will give you standard cost practically for your factory as imagined supra.
Ask such questions to yourself when you read, all the time.
Wish you best of luck.