Not sure where this guide originated, but I've adapted it from a thread on The Student Room here. It's a little old, but still applies absolutely to the 2015 AS exams.
How to Structure Your Exam Essays:
You gain four marks for your definition and four marks for your examples. Make sure that you define the key term and use as many other key words as you can to show that you understand the term. Make sure that you also include AT LEAST TWO examples, as with just one example you cannot gain the full four marks for examples.
It should take the form of two clear paragraphs, with each paragraph containing one point. You are being asked to explain two points, so make sure you do two - don't do one or three.
Twelve marks are given for your knowledge and understanding in this question, and you will need to include studies, concepts, theories or examples in each paragraph. You will get four marks for your answer being relevant and applied to the question; quite simply you need to ensure that your are answering the question.
This is the mini-essay. You will need an introduction, three/four points and a conclusion. If you are doing three points, make sure they are well explained. In this question, the use of studies and/or theory is pretty much a necessity to get a high mark.
Twelve marks are given for your knowledge and understanding in this question, and you will need to include studies, concepts, theories or examples for each of yours points. Eight marks are given for your answer being relevant and applied to the question, and four marks are given for your evaluation and analysis of the overall argument.
There are various ways to structure the 52 mark question, of which this is one:
First of all, you want to introduce your argument. That means that you will want to define the key concepts (so if the question is on ethnography, explain what an ethnography is in the pre-release). Your introduction can be brief, so don't spend too much time on it.
You want to cover four areas in your essay: reliability, validity, generalisability and representativeness. Within each of those areas, you will want to talk about the sample, method and data in the pre-release, and relate it back. So for example if you are talking about the reliability of a question talking about ethnography, you will start with a sentence that introduces reliability (the ability of being able to repeat the research and gain the same/similar results) and then apply that to the method - why the ethnographic method is or isn't reliable. Then you will want to (more briefly) apply reliability to the sample and data.
In your conclusion, you can mention things such as pilot studies, ethical issues and improvements that you would make to the research.
The most important part of this question is to ensure that you are, throughout, linking your answer back to the pre-release. You have been given it for a reason, so don't neglect it - if you aren't applying your points back to the pre-release, you are doing it wrong.