Take it step by step and always have a plan!
1. Read and reread the question. Do you understand it? Could you answer it in one sentence? What are the keywords?
2. Introduction - define any keywords in the question, outline your essay structure, give your argument
3. The main body - stick to short, cohesive paragraphs, each paragraph should support the answer to the question, also link back to your argument
4. Conclusion - Restate your argument, keep it short, don't say anything new