1) Plan your answer in pencil before you begin, making sure you sketch out all points that you're going to address. Even if it takes 5mins to do, it is pretty much all your work done, the rest is just translating your points into sentences.
2) Put different points in different paragraphs and make sure that at the end of every paragraph that you link the point you're making directly back to the question.
3) Don't stress if you don't know the exact date that something happened, just write an estimate of the date because getting the date wrong will not lose you marks, but putting in a date will give your answer a more sofisticated tone.
4) Keep it simple. Don't write too long about one point - a paragraph should be no more than five sentences, so you should only put in the information that helps answer the question.
5) Don't be afraid to enter in some of your own general knowledge. Many people are afraid to discuss what they haven't learnt in class, but if you're naturally knowledgable about a topic or have done some of your own research then why shouldn't you include it?
6) Don't make examples central to your answer. Your answer should be answering the question; that is the goal. Examples should be used to support your arguement, but your answer should be able to stand independently without examples. Examples should more be thought of as 'evidence' rather than a more central theme of the answer.