1) Manage your time at the beginning of your exam. Divide you’re an hour and a half or two hours into sections for planning, writing and reviewing. Always have a watch on your hand or check the clock in the exam hall to make sure you are on track of your plan.
2) Plan wisely. Plan your ‘points, evidence and explanation’ in paragraphs ahead, making sure your points are clearly tackling the key words in your question in a logical and organised way. In that sense, you have an advantage of making your essay more concise as well as focusing on the question rather than writing things not relevant.
3) Making sure you are prepared for the exam. Doing enough revision is an obvious thing to do before your exam but being familiar with the quotes particularly accelerate your thinking process in your head as you have already had the evidences, which are mostly presented by the quotes of your studied literatures. Constructing your points from your evidences is one of the most efficient way when you have a blank out in your exam.