How can we write a good essay about the selected piece of A-Level Literature e.g. L'etranger by Albert Camus?

This is a very common question because one of the major parts of the French written exam is the essay which will focus on an aspect of literature which the students have studied. Having achieved an A* in my French A-Level, I can say that this was in large part due to my essay writing skill and was comprised of following closely the specifications which my teachers gave me at the time. This includes knowing how to accurately structure this essay, writing an introduction,  three paragraphs which issues the essay will tackle and in which order and a satisfying conclusion (all of this in French of course!). I studied English Literature at A-Level as well so I feel I am very adept at this. Some other aspects of a succesful essay are: effectively embedding quotations and textual examples in the essay, using idioms to show varied knowledge as well using complex structures such as subjunctives etc. This is not only an example of a question which is very common for A-Level students but also something I can really help with!