Taking this sample A-level question on Hamlet, the most important thing to do is to establish a structure for the answer. The core of all good literary criticism is a coherent argument that moves from one point to the next in a logical manner; without this, the question will not be answered sufficiently. This question foregrounds Hamlet's 'disturbing fascination with death', and so immediately we need to set out the terms of our answer: how does Hamlet show a fascination with death? How is it disturbing? To what extent does this fascination characterise the play?
Hamlet is a vast and demanding text, which is why it is sensible to approach this question in stages - otherwise, we will find ourselves overwhelmed. These initial questions help to outline a structure for our argument: we know that death will be a primary consideration of our answer, but we will need to find examples within the text for support. That is what the first question deals with, and as an example, we might cite Hamlet's 'To be or not to be...' speech. How is that disturbing? That depends, we can say it is or it isn't: the great joy of English is that it does not prescribe interpretations. We would look in depth at Shakespeare's syntax and use of language - why do certain words or phrases have a particular effect? By studying the particular we can illuminate the whole. That leads us to the third question: having examined death in detail, we can place it in the wider context of the play. Is it the most important theme - what about love, revenge, desire, self-consciousness? That can be decided as we progress, as we weigh up the individual points and decide which one influences the place's direction the most. This is not about a formulaic exercise in ticking boxes, but to display a genuine understanding of a complex text, to establish a critical argument and pursue it to its conclusion. The particulars - the essay's style, how to integrate theoretical and secondary material - can be brought in later, but to have a framework for the answer is the most crucial thing of all.