I like these words.

"Jesus Christ, Son of God, have mercy on me the sinner."

• Jesus, whose name in Hebrew means God saves...
• To affirm that Jesus is the Christ implies that the whole history of the Old Testament is ours, that we accept it as the truth of God.
• We call him Son of God, because we know the man who was called 'Son of David' is the incarnate Son of God.
• These words sum up all we know/believe about Jesus Christ, from the Old Testament to the New, and from the experience of the Church through the ages.
• In these few words we make a complete and perfect profession of faith.
• But it is not enough to make this profession of faith; it is not enough to believe.
• ...recognition of our own sinfulness, our essential estrangement from God and the people around us.
• ...the cry for mercy of the publican, "God, be merciful to me, a sinner"
• we put ourselves face to face with Him, in the right state of mind: 'Have mercy on me, a sinner'.

(from http://www.goarch.org/en/ourfaith/articles/article7104.asp and http://home.it.net.au/~jgrapsas/pages/Jprayer.html )