What is the best way to brainstorm?

In class we have practiced different methods of writting. I don't know why but I feel that the best way is make a Mapping. In class I felt more confortable and secure making this, is better for me because is easily link some ideas and later write complete sentences about them.
An example of mapping:

We can make different mapping as we want, and choose different topics, they don't have to be related. When we're done we have to make a drafting with all the topics we have created and then we have to make a connection among them.

There are different methods to make an essay but this is the most comfortable and the one that helped me because is easier to create ideas.