I was reading through this book given to me by my friend Josh.
The following thoughts were helpful:
"Thy typical evangelistic prayer focuses on praying for the lost. This is certainly appropriate, but the clear emphasis in Scripture is to pray in a different direction. Jesus' burden for the lost multitude resulted in His instruction to pray that the Lord would send laborers into the harvest field (Matthew 9:38). In His deep burden for the unsaved He commanded prayer for the saints instead of the sinner. Likewise Paul requested prayer for both the opportunity to witness (Colossians 4:3) and the courage to present the gospel (Ephesians 6:19-20). To pray for our lost friends is a naturally loving instinct, but it is God's Word that guides us how to do so."