You may have other sentences before the thesis statement which is normally positioned in the middle of the first paragraph. But these are all pointers to the statement and the points that really kick starts your thesis are contained in the statement. The rudiments of the thesis statement, which is to serve as the starting point in your thesis writing and this you must learn and master if you really want to know how to start a thesis, are numerous. First of all, it must state the arguments and points you wish to posit in the main paper, it should be the roadmap that will drive and align all your thoughts, arguments and analyses in the paper. When you want to write a good thesis statement, you have to ask yourself, what is this paper about? If the statement answers the question well, then you have learnt how to start a thesis.