How do Lady Macbeth and the witches manipulate Macbeth?

This is a good question. I think the witches have a lot of influence on Macbeth. Keep in mind that they can't make him do anything. Their suggestions drive Macbeth to go on his murderous rampage. Although a good soldier, Macbeth is insecure and riddled with doubt. He likes the idea of being King but is scared to play "foully" for it. Lady Macbeth seems to have more power over him, at least initially. Still, as the play goes on and Macbeth slips deeper and deeper into his own madness, the witches play a greater influence. They tell him what he wants to know, through their riddles, and this contributes to his final undoing. Macbeth knows how to manipulate her husband. Her usual "go to" manipulation is to question his manhood. She knows her husband's insecurities and exploits them to "catch the nearest crown".