As a reminder, the thesis statement (TS) is the most important sentence of any paper you write and should be written before any other part of your paper. Your TS is the beacon for the rest of the paper and the body of your paper must follow and reinforce your TS.
Because your TS is the most critical part of your paper, you should write and edit it before you write any other part of your paper. If your TS is good, it is likely that the rest of your paper is good; if your TS is bad, it is highly likely your whole paper will be bad.

Below is a good six-part test to determine if you have a good TS:

1. Does it answer the question clearly and directly?

2. Does it tell you what you are going to cover in your paper; is it a good road map for your paper?

3. Does it have a point of view and include your opinion?

4. Does it engage the reader? Is it interesting, and thus memorable to the reader?

5. Does it answer the "so what" question? Why should the reader care about your point of view? Why is this important to the reader?

6. Is the writing sharp, crisp, and to the point?