I think that one distinct starting point in writing about the tragic hero that Othello is might be to talk about his downfall. Part of what makes Othello so tragic is because his greatness and sense of awe could not offset his own insecurity. Shakespeare's genius is to construct a character that could appear to represent so much to so many on the outside, only to be plagued with internal demons that lead to his downfall. A great warrior, a self- made man, and one who represents some of the very best qualities is beset with insecurity and doubt about who he is and what he deserves. He is a warrior in a setting of politicians. He is a man of color in a world where he is the most visible of minorities. He is an outsider who has made it within the inner circle.
Running through all of these dynamics is the fact that Othello is insecure. He finds it difficult that someone like him would be where he is. He cannot fathom that someone like Desdemona would choose someone like him, seen in moments such as when he says, "she had eyes and chose me." It is within this small sliver of insecurity that Iago strikes. He magnifies the fatal flaw within Othello. I think that being able to discuss how Othello's sense of greatness is offset by his insecurities might be a very good starting point in terms of exploring the tragic condition of Shakespeare's protagonist.