No writer can generate a perfect draft on the first attempt. Most employ a writing process, in which they begin with prewriting and invention, then outlining, composing, revising and editing. Though the aforementioned might suggest a linear process, it is usually recursive. For instance, you might end up going back to the prewriting phase and do some brainstorming even while writing the actual draft. The general rule of thumb is to invest some time brainstorming and writing a rough outline before writing the essay. Also, save editing for last. Sometimes it may be too difficult to juggle developing your ideas along with attending to grammar so save editing for the very last step.
First of all, you should read the introduction which discusses the question: "What can I do to increase my creativity?" Random Input Problem Reversal Ask Questions Applied Imagination - Question Summary Lateral Thinking Six Thinking Hats The Discontinuity Principle Checklists Brainstorming ...