The joy of history essays is that their structures can actually be very formulaic, which means that once you've learnt and practiced the technique, you can show off your knowledge to full advantage. Firstly, identify what conclusions the question is asking you to decide between. The questions will usually include a phrase such as "how far", "how far do you agree", "to what extent", or "what was the most important factor". This essentially means you need to debate the importance of different factors that affected a certain result, and then come to a logical conclusion based on your argument. So for instance, if the essay question is "How important was the dissolution of the monasteries in bringing about religious change in England?", you would write about six paragraphs aside from your introduction and conclusion. The first two to four paragraphs (depending on how significant you think the dissolution was in bringing about religious change) would discuss the ways in which the dissolution of the monasteries brought about religious change. The remaining paragraphs would debate other factors that brought about religious change. Your intro and conclusion can be short and succinct - the former just outlines what themes you're going to discuss, and the latter explains why you've decided on the most important factor over the others.