In June the author completed her first full year of high school teaching. In this article, she shares her top 10 mistakes for several reasons: (1) so that other beginners will know what to expect; (2) so that teacher educators will share with candidates for licensure; (3) so that she won't make the same mistakes again; (4) so that veteran teachers will remember and support new teachers; and (5) because teachers are told that reflection in education is important.