Here are two traditional prayers for Good Friday.  Apologies for waiting until Saturday morning to put them up!  There will be prayers for Saturday and Easter Sunday as well.

From the Lutheran Book of Prayer:
O Christ, Lamb of God, slain for the sin of the whole world, with penitent heart I come to your cross, pleading for mercy and forgiveness.  My sins - and they are many - have added to the burden of Your suffering and have nailed You to the accursed tree.  For me You tasted the agony of the utter darkness that I might not perish, but have everlasting life.  Have mercy upon me.O Christ, Lamb of God, embrace me with Your love, and forgive me all my sins.  Your death brings healing to my soul, peace to my mind, cleansing to my heart.  If You would mark iniquity, I could not come, for my hands are unclean, my lips are sullied, and my heart is blackened by sin.  But beholding You bleeding, despised, forsaken, dying, pierced, I come to be cleansed and forgiven.O Christ, Lamb of God, grant that I may hate sin and wickedness more and more as I behold You in Your great agony.  My grateful heart today finds hope in Your words, comfort in Your promises, and salvation in Your finished work on the cross, by which You have overcome sin, Satan, and death.O Lord, have mercy.  O Christ, have mercy.  O Lord, hear my prayer.  Amen.
From The Book of Common Prayer:
Almighty God, we beseech thee graciously to behold this thy family, for which our Lord Jesus Christ was contented to be betrayed, and given up into the hands of sinners, and to suffer death upon the cross; who now liveth and reigneth with thee and the Holy Ghost, on God, world without end.  Amen.
World without end, Amen!