Because an opinion is a view that is not generally based on fact or knowledge, it is important for you, the writer, to give solid reasons for your opinion. Once you have stated your opinion in your thesis statement, you will want to support it with explanations, facts, and/or experiences.

Explanations

You will not be able to prove your explanations, but they will help your readers understand why you have formed your opinions, and they are important to you.

Facts

Facts on the other hand, whether historical, scientific, or just general knowledge, will make your opinion more plausible.

Experience

Experiences, especially  personal experiences, are convincing and show your readers why your opinion is real. Experiences can also help readers relate and connect to your situation better, which in turn will help them understand and accept your opinion.

Examples

• Opinion: Chinese is a difficult language to learn.
• Explanation: When studying Chinese, you need to study five to six hours a day to master basic communication.
• Fact: Chinese is an ancient language dating back some three to five thousands years.
• Experience: I studied Chinese Characters until I could read basic scripts fluently.