Final answer:
A topic paragraph in writing should have a clear focus, a main point expressed in a topic sentence, and supporting evidence and analysis to develop the topic. Transitions should be used to maintain flow, and a new paragraph should be started only when a new topic is introduced.
Step-by-step explanation:
A topic paragraph should address specific questions and maintain a clear and unified focus. The paragraph should start with a topic sentence that expresses the main point, which can be located at the beginning or elsewhere in the paragraph. Supporting evidence and analysis should be provided to develop the topic, including examples, comparisons, contrasts, causes, or effects. Transitions should be used to ensure the paragraph flows smoothly, and a new paragraph should be introduced only when a new topic is introduced.