I've wondered sometimes how we should apply this. What does it mean to become like one not under God's law? In what ways do we become like those we are trying to reach? In what ways did Paul become like those he saught to love into the truth. Maybe in every way that DIDN'T matter...? Maybe the key point is v19, becoming a servant. Doing everything possible to love and bless others in a way that THEY will understand rather than in a way that WE will understand.
I don't know about you but I find that tough!

Check out The Message translation on this section!

1 Corinthians 9:19-22