How does Macbeth almost ruin the plan to kill duncan?

Macbeth almost ruins the plan to kill Duncan by being too hesitant and indecisive. He is constantly second-guessing himself and worrying about the consequences of his actions. This indecisiveness leads to him making several mistakes, such as leaving the daggers at the scene of the crime and not being able to bring himself to kill Duncan while he is sleeping. As a result of these mistakes, Macbeth's plan is nearly discovered and he is forced to improvise in order to save himself.