The more examples you give, the more persuasive you become in your writing. But be careful! You must be aware of not just your side of the argument, but also the one of your opponent.
Acknowledgment of the opposing views is called concession. School uniform may apply restrictions on appearance of the schoolchildren, but they do not restrain from getting knowledge, as it main goal of studying. Start with a thesis statement. Then refute those with even stronger arguments.
Questions to answer before choosing an essay hook: How do I want my readers to feel?