Blood, what does it mean???? Life, death, guilt, vengeance? Come and find out........

Act: 1 Scene: 7---
"...but in these cases
We still have judgment here; that we but teach
BLOODY instructions , which being taught return
To plague the inventor:" 

At this point in the play, Macbeth is in his castle contemplating whether or not he should kill King Duncan. Macbeth is not strong willed at this point and cannot decide whether to follow his wife's council in the murdering of King Duncan or to be loyal to his King and cousin. He lists reasons for not killing Duncan and believes that by killing Duncan he would be teaching bloody instruction that would come back to plague him. 
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The word 'bloody' in this sense is figurative and means evil or corrupt. The phrase 'bloody instruction' means 'corrupt instruction' which refers to Lady Macbeth's corrupt instruction to Macbeth of how to murder Duncan. This line illustrates how the word 'blood' often has a negative or unhappy connotation.

Act:1 Scene: 7--
"When we have mark'd with blood those sleepy two of his own chamber, and used their very daggers that they have done't?"

In this scene Lady Macbeth and Macbeth are planning to stage Duncan's murder as if his guards had killed him. They plan to put the guards to sleep and use their daggers to kill Duncan and then return the daggers to the guards' bolsters. When the bloodied daggers are found with the guards, they will be punished for killing the king instead of Macbeth. 
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The word blood in this scene is used both literally and figuratively. The guards' daggers will indeed be covered in blood which will make the guards appear responsible of the murder, but also the word blood signifies guilt. When the blood is seen on the daggers, the guards will look guilty of the crime and be punished accordingly. In this scene, the phrase 'mark'd with blood' is a bad thing that will soon lead to death, but in the bible during the first Passover, the doors of the Jews' houses were 'mark'd with blood' and they were saved from the angel of death, which was a good thing. Therefore, being marked with blood is not always a bad thing, but in this case is.

Act:2 Scene: 2--
"Will all great Neptune's ocean wash this blood clean from my hand? No'"

In this scene, Macbeth has already killed Duncan and has mistakenly brought back the bloodied daggers. Lady Macbeth scorns him for being cowardly and goes to return the daggers because Macbeth is too fearful. Now Macbeth is regretful and ashamed and wishes that he could undo his terrible deed. While Lady Macbeth appears bold and brave, Macbeth is openly fearful and sorrowful. He knows that no amount of water will ever take away the guilt and blood from his hands.
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In this scene the word blood is figurative and signifies guilt. This scene shows Macbeth's guilty conscience and remorse after shedding innocent blood. Like a deep stain that is impossible to remove, Macbeth knows that he will never be forgiven for his deed and so he must suffer with guilt, i.e., blood on his hand.

Act: 2 Scene: 3

"Here lay Duncan, his silver skin laced with his golden blood."

At this point in the play, Duncan has been found dead by Donalbain and Malcolm. They assume that the guards have killed Duncan because of the bloodied daggers. Everyone is in shock and alarm as Macbeth speaks this quote. 

In this quote, the word blood is figurative in the sense that the blood on his dead body is being described. Also, phrase 'golden blood' is worded in such a way that shows Duncan's royalty. No other character's blood was described as golden in the play. This could be because he was the king at the time or it could possibly show his innocence. Just like the phrase 'a golden child' means an innocent and perfect child, the phrase 'golden blood' could refer to Duncan's innocence.