And this represents the four components that must be present in a paragraph. Now I'm not talking about sentences, but about components. So bear with me if this is new to you. So, a paragraph should always start with the main idea or topic sentence. It should always include both evidence and analysis. Evidence and analysis are combined: Identify the topic sentence. The first thing you need to do is analyze the paragraph and identify the topic sentence. You probably learned to give each paragraph a topic sentence in high school. The topic sentence should introduce the main idea. Ideally, the topic sentence should be directly related to the thesis statement, which.