Outlaws snipe things. The best exp is sniping the two on the left in the middle. If the middle is taken, then snipe the two on the left on the bottom.
Edit: The strategy is Freeze -> Burstx4. If you can kill a newtie in 6 hits or less (not including Ice Splitter), then you don't have to freeze it more than once. That's pretty much the whole thing.