Remember not to get too carried away and overload your writing with too many obvious connectives and contrastives. If every sentence has 2 or 3 of those words or expressions, then the writing can become strained and artificial.
The goal of the essay is to write for or against a topic and be able to effectively provide reasonings behind your stand. Too many big words break the fluency of the essay and risk the possibility of getting points deducted from your score.