In Macbeth, from the moment that Lady Macbeth receives Macbeth's letter advising her of the witches' prophecies, Lady Macbeth begins scheming to make Macbeth king the "nearest" (Act I.scene v.line 15) (as in the quickest) way. She does not think that Macbeth will be able to fulfill the prophecies without her help because she says he is "too full of the milk of human kindness" (14). She intends, therefore, to "pour my spirits in thine ear" (23) and do all that she can to remove any obstacles that have the potential to stop what "fate" (26) has deemed should happen. To be certain that she can deliver, she even begs the spirits to "unsex me here" (38) so that she will not be tempted, in seeing "the wound it makes" (49), to stop. Lady Macbeth also tells Macbeth not to worry as she will make all the necessary arrangements.
In convincing Macbeth that they will not fail in their quest to make him king, Lady Macbeth explains to Macbeth that, when Duncan is asleep, she will offer wine (which she will drug) to his "two chamberlains" (I.vii.63), his guards, and the men will get drunk; where-after, they will sleep deeply "as in a death" (68), which means that she and Macbeth will be able to do anything they want to the "unguarded Duncan" (70). She points out that they will place the blame squarely on the guards and will themselves, make such a commotion upon hearing of Duncan's murder that no one will suspect. This is sufficient to persuade Macbeth to go ahead with the plan.
Lady Macbeth then leaves everything ready; the door open, the guards drugged and drunk and the daggers with which to kill Duncan in place. While she waits for Macbeth to actually kill Duncan, she feels sorry that she was unable to perform the deed herself, commenting to herself that Duncan resembles her own father "as he slept" (II.ii.13). This prevents her from killing him herself, which she would have preferred, in fact, because then she would not have to worry about Macbeth's ability.
Lady Macbeth's plan includes having King Duncan stabbed to death with daggers and framing the guards (who will be drugged and unable to react to the murder) in his room by rubbing them with the king's blood. She will signal Macbeth when it is time for him to go to the King's quarters to do the deed. Yes, she does gaze upon the sleeping Duncan and remark that he resembles her own father. This is the first time in the play that we get the feeling she has a heart and is capable of human compassion--of course, later on she begins showing her weakness and guilt by sleepwalking and committing suicide.