Write down what you plan to cover and why. This will help you to budget your time. This structure will help you get things done on time. Otherwise, the temptation is to set a date when the final draft is due and turn in the draft at the last minute. This won't work.
Data collection is tremendously time consuming.
Make sure that you allow enough time. Invariably, measurements have to be redone, statistics recalculated, and interviews followed up on. A general rule is to allow twice as much time as you think you need. Before you begin writing you should get the two essential writing manuals listed below. Get them and read them.