This video does a pretty good job explaining how to outline for an essay. Keep in mind that you want to keep your ideas as short as possible so they are easier to see at a glance and that you don’t need to use roman numerals if you don’t want to. Dots and dashes or arrows and stars work just as well. The important thing is making each level distinct. Also, it is a good idea to write your complete thesis statement at the top of your outline rather than just the topic.