When writing any essay, you must always include an introduction, a main body of text, and a conclusion. It's like a sandwich, with the good meaty stuff right in the middle.
The introduction, in any essay, needs to directly address the question and outline the key points that you will be focussing on in your essay. These should be the main points that you will be exploring in the main body of your essay.
The main body of the essay should be comprised of a few chunks (separate paragraphs), and it would be easiest to arrange these by doing a point per paragraph. There is no set way to know how many paragraphs your essay should be, but if you stick to a point per paragraph, then this keeps your essay nicely organised and concise.
For each of your main paragraphs, I find it most helpful to use the PEE technique. However, I was once taught by a very good teacher to elaborate even further on this method, and actually PEEEE (Point, Example, Explain, Explore, Evaluate). The PEE method is the basic layout for this, but once you have covered your explanation, to earn the top marks it is best to explore this idea in further ways, and then sum up each individual argument.
The conclusion needs to sum up the points you've already made and really emphasise your ARGUMENT. You should never introduce new points to your conclusion, because this makes it look like you have not really planned the essay!