'Planning' or 'Brainstorming' as it is popularly called is important for good writing.
It is vital before you start any writing task to make a plan first.
Although you usually don't get marks for your plan, it will help make your writing more organised and of course you do get marks for that.
How do you make a plan? Firstly by thinking about the question and deciding what you will write about. Your plan is usually a list of what you will write.
Remember the 'WH-' questions
when why what who where
some of these questions will be relevant to the situation, others will not.
remember planning only takes about 5 mins.
Sometimes it is helpful for 1-2 minutes to write down everything you know about the subject. Then you need to look at this and decide which information will help you answer the question. Be selective choose only the points that answer the question.