Though your thesis is essentially your personal opinion, it needs to be presented as a structured argument.   Your thesis is a statement that others may hold a different opinion about. And which you will develop in your essay to show why you have this point of view. Check to make sure your thesis contains an argument that hits on the focus of your question. Revising your seatbelt thesis to: “Increasing seatbelt laws to include mandatory buckling in back seats will provide further safety benefits by reducing the percentage of fatalities in vehicle accidents.” better answers your original question. A very vague, large statement will require many pages for you to support adequately. A highly specific idea may not be a strong enough argument or provide enough evidence to back up.  While “The fear of muddled class systems and the pursuit of the American Dream depicted in The Great Gatsby led to an age of consumerism and excess, which triggered The Great Depression.” answers your question, it’s slightly broad. “The themes of wealth disparity in American royalty, and pursuit of the American Dream presented in The Great Gatsby depict a parallel to real-world consumerism and excess which led to the Great Depression.” narrows down that you will talk about specific themes in the book and compare these fictional themes to the real world. This is also an example of a thesis statement which can be broken up into two sentences. Now that you’ve compiled evidence, revised, and come to a specific stance, read over the assignment again. Make sure that you can write a paper with your current thesis that will fulfill the requirements.  If your assignment was to discuss the benefits of seatbelts, read your thesis again and ask yourself if it can cover the criteria. “Increasing seatbelt laws to include mandatory buckling in back seats will provide further safety benefits by reducing the percentage of fatalities in vehicle accidents.” In this thesis, you have taken a position that can be argued. You have made it specific by narrowing your topic a particular aspect of seatbelt safety. And you have given an answer to how your argument will discuss the benefits of seatbelts. If you’ve already done some research, which you should have to arrive at your thesis, you should be able to provide enough evidence throughout your essay to back up your claim.   Before beginning your paper, make sure you have fulfilled all the criteria. Do you answer a question? Are you taking a position others can challenge or oppose? Is your thesis specific enough? Does it pass the “So what?” and “how and why?” test. If your thesis doesn’t fulfill these requirements, take a break and then go back and revise. Sometimes, after taking a step back, you can come back with a better angle. As you write your essay, follow your thesis and outline, but don’t feel that you have to compromise your paper to fit your thesis. If you find yourself needing to revise your thesis throughout your essay, do so.

Summary:
Make sure your thesis has an arguable point, that is not too general a fact or solely a personal opinion. Strike a balance between being too vague and too specific in your thesis. Make sure your thesis covers the assignment. Make sure you can accurately explain your ideas well enough in your essay to support your thesis.