Fortunately, the conditions under which a TA will read your essay are much like those in which everything else you ever write will be read, from reports written for your future employer to love letters written to your future spouse. This means the skills required to write these papers are generally applicable in life. Especially with dealing with an inattentive reader who isn’t especially interested in your thoughts, a special effort must be made to put forward an argument that will lead the reader along while rewarding their attention. In every case, the reader will have other demands on their time and other things on their mind. Your purpose is to convey something convincing and scholarly under those conditions. Your two real tasks are to develop an argument and then to convey it in as clear a way as possible.