Brainstorm ideas by writing down words and phrases that pop into your head when considering a topic. Brainstorming usually takes the form of a list of loosely related words and phrases.
Cluster ideas into bubbles for a more visual approach to brainstorming. Begin with a single idea in a circle, then draw lines to other circles containing ideas that relate to the first idea. This can help group ideas into organized categories.
Write all the ideas you have about a topic in paragraph form. This technique, freewriting, encourages you to just start writing if you're having a hard time getting started. If you don't have any ideas about a topic, start freewriting about how you don't have any ideas about a topic, and you will likely discover you do have ideas.
Read what you've written, crossing out ideas that don't work and highlighting ideas that do. It may be useful to do another round of prewriting once you have narrowed your thoughts.
Make an outline: a list of points you plan to write about organized into the order you plan to write them. Outlines can help ensure that your writing is organized and logical.