Brainstorm ideas for an overall topic or theme for your paper. Brainstorming will help you generate ideas for your thesis. If you have to respond to a specific question, your thesis will be the answer to that question. If you have to write on a topic, your thesis will be your stance on that topic.
Write down several possible directions to take with your paper. You can use any format that works for you, whether it is simply writing down whatever comes to mind, developing an outline, or some other form of pre-writing. This will help you decide which ideas you know the most about, and which ones you would enjoy writing on the most. Good thesis statements involve ideas that you feel strongly about.
Write your thesis down in a clearly stated, positive sentence. A positive statement says what something did rather than what something didn't do. For example, if you were writing a paper about study habits, a positive thesis statement would be, "Students who study an hour each day improve their test scores." A negative thesis statement on the same subject would be, "Students who do not study each day do not improve their test scores."
Review your thesis. A strong thesis makes a specific claim, and often answers questions like "How?" and "Why?" The study habits example is a relatively strong thesis because it clearly states why the students' test scores improved. It could be made even stronger with more specific data. "Students who study every day improve their test scores by 10 percent" is an even stronger thesis statement because it makes a very specific claim.