The play tends to center on his role as the following: Warrior, Murderer / Usurper, Husband, Tyrant King and Traitor.
Primarily, the character traits Macbeth exhibits are as follows: bravery, loyalty, warrior's capability (he's a killer); ambition, weakness, reflectiveness, fearfulness, pride, and guilt. This is just a few of them, and I'm certain there can be an argument for more. The thing you will need are the quotations, the evidence that exhibit these characteristics; so let's take a look at a few:
Captain about his role of a warrior and subject to the King: "For brave Macbeth--well he deserves that name / Disdaining Fortune, with his brandished steel..." (I.2.16-17). The captain here explains to King Duncan how heroic Macbeth is on the battlefield as he fights against the Norweyans.
Macbeth as a subject to the King and his loyalty: "The service and the loyalty I owe... / ...and our duties / Are to your throne and state children and servants" (I.5.22-25). Here, Macbeth exhibits his loyalty to the King and Scotland.
Macbeth as assassin and his weakness: "We will proceed no further in this business: / He [the King] hath honored me of late" (I.7.31-32). Macbeth shows a bit of weakness, not wanting to go through with the murder, trying to talk himself out of it. It's his wife, however, who pushes him to the next level, questioning his manhood.
Macbeth's reflective nature as a Husband and traitor: "She should have died herafter... / Life's but a walking shadow..." (V.5.17-28). This entire passage unveils a reflective nature about Macbeth, who is contemplating life and dead, just after he hears the news of Lady Macbeth's demise. He seems to come to terms with the ending of all things, a realization about himself and his kingdom and his life.
The final fight scene between he and Macduff could represent a sense of pride and arrogance and stubborness from the Thane and Tyrant King. And his speech just before the murder of Duncan in Act 2 ("Is this the dagger I see before me?"), demonstrate a sense of guilt and contemplation as well, during his role as a murderer.