Read the thesis statement thoroughly and ask whether it answers the question presented as the topic. A good thesis will always answer the question.
Look for an argument against your thesis. A thesis statement must always have a potential argument or different point of view. If it does not, the thesis statement is not appropriate because it is more a summary than a point.
Avoid vague language, which makes the thesis weak. If a word is vague, unclear or can be replaced with a more specific word, you must change the wording.
Read the essay and ensure that the thesis fits the ideas in the essay. If the points in the essay do not match the thesis statement, the statement or the essay must be changed to reflect the points. Or you can change your thesis.