For writing a good thesis statement for a persuasive essay, you have to follow the following guidelines:
a. The thesis must be a complete sentence. By definition, a thesis makes a claim about a subject. You have to stick your neck out and make a point. Therefore for a persuasive essay, description of the subject is not sufficient; it should have a valid thesis statement.
b. A thesis must be an assertion, not a question. A question may be used effectively in your title or introduction as a way of creating interest, but a thesis is a statement that answers the question in your persuasive essay.
c. The thesis must be a generalization or an opinion, not just a statement of fact. A fact is something that can be verified as true or false; an opinion is something that must be supported or proved. So, the thesis statement for a persuasive essay should be an opinion or generalization.
d. Thesis on a controversial subject should not be wishy-washy. You may feel that there are good arguments on both sides, but you should make some assessment of the issue for a persuasive essay.
e. A thesis should make a point, not just promise to do so. For every claim, you should give justifications for your claim for writing a good persuasive essay.
f. Ideally, a thesis should be stated as a single statement that should also give the main idea.
g. Learning to combine a group of ideas into a single sentence takes a bit of practice. Therefore, for writing a persuasive essay, you should write a clear and understandable thesis statement that will make your essay a persuasive one.