How to write a essay about Macbeth Motifs?

So my topic is "How do motifs help farther character development in Macbeth". So far my thesis statement is

Throughout the play Macbeth, Shakespeare uses motifs like blood, sleep, and darkness to help farther character development.

I know it seems really bad, but can i get some help on it please? Some suggestions or even a better thesis would help. Also if any other 'motifs' would be a better pick. Thanks.

for motifs there are the prophecies come true, the witches' prophecy that Macbeth will become first thane of Cawdor and then king, they tell us that Banquo's heirs will be kings, that Macbeth should beware Macduff, that Macbeth is safe till Birnam Wood comes to Dunsinane, and that no man born of woman can harm Macbeth. Violence and hallucinations, when Macbeth is about to kill Duncan, and sees a dagger floating in the air.