Wounds of a friend...

Do you ever just ache for a friend in trouble? You know, that friend who just seems to keep making choices that are either self destructive or just shockingly stupid? What do you do? How do you respond? I've been struggling with this for a while. What exactly are we as Christians supposed to do when our Christian friends are screwing up? What are we supposed to do when they're sinning on purpose? What are we supposed to do when their actions are so unbelievable that your guts hurt and your head refuses to wrap around the possibility that your friend has become THAT lost and THAT broken and THAT careless? I know the Bible says "Faithful are the wounds of a friend..." and that we aren't supposed to just sit by, but what exactly are we supposed to DO? What's the right way to "wound" a friend in order for them to be drawn back to Jesus and His ways? How do you love them in a way that shows them that Christ's love is all encompassing? I'm searching this out. I'm praying for wisdom. I want to speak words that the Holy Spirit wants spoken. I want to listen with ears that Jesus has opened. I want to love the way the Father loves me. I want my friends to be whole, to return to Truth. I want to see-no- I NEED to see God's miraculous rescue in the lives of my friends. If I'm to be part of that rescue, oh God, please help!