The Bible clearly teaches that God uses His angels to minister to His people, sometimes clearly as guardians over their lives. Consider the following passages: (All taken from the NKJV)
Psalm 91:11 - "For He shall give His angels charge over you, to keep you in all your ways."
Hebrews 1:14 - "Are they [angels] not all ministering spirits sent forth to minister for those who will inherit salvation?"
Psalm 34:7 - "The angel of the Lord encamps all around those who fear Him, and delivers them."
2 Kings 6:17 - "And Elisha prayed, and said, 'Lord, I pray, open his eyes that he may see.' Then the Lord opened the eyes of the young man, and he saw. And behold, the mountain was full of horses and chariots of fire all around Elisha."
Matthew 4:11 - "Then the devil left Him, and behold, angels came and ministered to Him."
Matthew 18:10 - "Take heed that you do not despise one of these little ones, for I say to you that in heaven their angels always see the face of My Father who is in heaven."
Acts 27:21-25 - "...Paul stood in the midst of them and said, 'Men...there stood by me this night an angel of the God to whom I belong and whom I serve, saying, 'Do not be afraid, Paul: you must be brought before Caesar; and indeed God has granted you all those who sail with you.' Therefore take heart, men, for I believe God that it will be just as it was told me.'"