If there is a word count for your essay try to devote 10% of this to your introduction.
Ideally the introduction should; Introductions are very important as first impressions count and they can create a halo effect in the mind of the lecturer grading your essay.
Before you write your essay it's important to analyse the task and understand exactly what the essay question is asking.
It is possible your lecturer will give you some advice - pay attention to this as it will help you plan your answer.
There should also be an appropriate balance between these two essay components. Most students make the mistake of writing too much knowledge and not enough evaluation (which is the difficult bit).
It is best to structure your essay according to key themes.
However, reading and planning will make the essay writing process easier, quicker, and ensure a higher quality essay is produced.
Now let us look at what constitutes a good essay in psychology. In the main body of the essay every paragraph should demonstrate both knowledge and critical evaluation.
It is very important to elaborate on your evaluation.
Don't just write a shopping list of brief (one or two sentence) evaluation points.