Make a circle in the middle of the piece of paper and write the name of the character you want to describe. If you're writing about Willy Wonka, write his name in that circle.
Draw lines radiating out from this circle and draw circles at the end of each. You will need one line for each characteristic you want to use; anywhere between four and eight will work for most essays.
Insert a trait of your character in each of those circles. In the case of Willy Wonka, words such as "creative," "whimsical," "compassionate," "odd" and others might go in those circles.
Draw two lines radiating out from each of those outer circles, and add circles at the end of those lines.
Insert details that support the trait to which the circles attach. For example, around "brilliant," you might put details such as "invented the Great Glass Elevator" and "perceived that Charlie should run the factory."
Follow your thinking around the web as you organize and write your essay.