What's the Difference in Blessings?

When you bless some one, all youre doing is asking that god do something nice for this person. Martin asks, what's the difference in blessings? I bless myself and my children. How effective that versing verses a blessing done by a priest? There's not a hard and fast answer to this that the church has provided. Anyone can ask god for a favor, either for himself or for another person. The question is, will god listen to that person?