You are right. But there are no clear criteria for any paper. I have learnt in my journey that one should take each paper separately and learn and analyze its own techniques.

As far as essay is concerned, after taking guidance from top three teachers in Lahore, I have made my own strategy and it worked.
Outline and thesis statement of essay must be clear and to the point. Mostly students write some irrelevant headings and contents and they get failed.

For example, if an essay ask one dimension of education or democracy, students write importance, meaning etc. which have not been asked.