Luke 1:45 And blessed is she that believed: for there shall be a performance of those things which were told her from the Lord.
Mary was blessed because she had believed the promise of the Lord through the angel. What she was told would be coming true.
Please focus on the fact that she was blessed. She is the recipient, not the source. God gave her blessings. It was her faith. She believed. Too often we idolize people that have been blessed. We even begin to consider them to be the source of blessings for us. Mary was being given benefits by God.
Always look to God, the only One, that can indeed bless. He will keep His Word not due to our goodness or merit because of His character and kindness. He is God, and there is no other. No one else is worthy of our praise or prayers.