How to brainstorm when writing an essay?

According to Catherine Schwerin’s guideline, when we want to write an essay, we need to follow these four steps: Preparing, Brainstorming, Organising & Adapting, and Final Plan. First of all, we establish a thesis such as 'Brainstorming is very needed to write an essay', so now we have the given subject 'brainstorming' and its specific purpose 'to write an essay'. In the second step, the more you brainstorm about the topic, the more you need to write down on a paper. Once you write down these ideas which you have recently brainstormed, they will help you organise the content, and you will help them not be forgotten while formulating the essay. For example, with regard to the topic 'brainstorming & essay', you can write down such key words as 'preparation', 'imagination', 'creative', 'structure', 'solution', etc. And it is not necessary at all to worry about the relevancy of ideas; you just need to get yourself into 'stream of consciousness' and let all of them flow out to paper freely and spontaneously. When you want to valuate or/and order these ideas and then to express them properly, that is what you have to do respectively in the third and fourth step afterwards.