You need to identify appropriate rhetorical patterns for the topic and the task, and identify the components of an effective thesis statement. Hope this helped! :)
Everything you need to make a good meaningful sentence (and grammatically correct, ofcourse), is to follow common rules. Do not forget to provide your sentence with complexity, but you dont have to make them too complicated, I mean you need to use key words, they will make your thought completed. And the second point is that you need to properly organize the sentence using correct word order.