The Shepherds were out in the fields watching their flocks by night.

Read Genesis 35:19-20.  It tells how Rachel died "and was buried on the way to Ephrath (that is, Bethlehem)" and how Jacob went on and "pitched his tent beyond the tower of Eder."

Then read Jeremiah 31:15-16.  It tells about "Rachel weeping for her children".  It is at Ramah that the people of Judah were gathered, chained and roped together, and led off to exile in Babylon.  But verse 16 says, "Keep your voice from weeping . . . they shall come back from the land of the enemy."

Putting those two passages together (1) God gives hope for the mothers of Bethlehem whose children were killed by Herod -- "they shall come back." But also (2) the Rabbis expected that the first announcement of the coming Messiah would be at "Migdol Eder;" the "tower of Eder."   Eder means flock (as in flock of sheep), so "Migdol Eder" means "Tower of the Flock."  Look up Luke 2:8-11 and see if they were right.

Why were the shepherds out in the fields at night?  Most sheep are brought into the sheepfold where they are safer.  But Bethlehem is close to Jerusalem.  Sheep that were destined to be sacrificial sheep at the Temple had to be kept outside, in nature not in buildings all the time.  Shepherds built towers to more easily watch their sheep.
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So the angels went to shepherds watching over sacrificial sheep to tell them about the One Lamb, the Lamb of God who takes away the sin of the world.  This is amazingly appropriate, isn't it?

According to Rabbinic tradition the name of the Messiah was concealed from eternity, to be revealed only when the time was right.  So the revealing of the name was tremendously important.  A lot of details about Jesus are already told in the Old Testament – where He would be born, when He would be born, which tribe of Israel He would be from, etc. – but not His name.

The name Jesus was independently revealed to both Mary and Joseph.  If you read through Isaiah 7:14 you would expect His name to be Immanuel.  But . . . first the angel appeared to Mary and told her she would bear the Savior of the world and told her to call Him Jesus.  Then Joseph found out that she was pregnant and did not believe her.  Only then did an angel appear to him in a dream and tell him to call the baby Jesus. 
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The name "Jesus" was revealed to both Mary and Joseph, to each one of them independently.  This is one example of God’s Word being corroborated by matching dreams, visions, or revelations.  (See also Paul & Ananias in Acts 9 and Peter & Cornelius in Acts 10.)  This is important in confirming Mary's truthfulness and that the dream Joseph had really was from God.