Rip Tide's 60/20/20 formula is dead on to rights. Works like absolute magic. I throw poppers at pretty good distances on a slow action 6 WT rod all the time. Here's what I do:
For poppers, I start with 15 feet of 10# (seldom heavier) monofilament. If I were throwing streamers, I'd go with fluorocarbon. I make a twisted leader, with the butt section at least half the length, but most often it is about 60/20/20, just like Rip Tide said. You'll end up with a twisted leader about 4 & 1/2 feet long, with loop to loop connections on both ends if you did it right. Put a foot and a half of 10# (or your favorite) monofilament on it as a tippet, and you're in business with a leader that is 6 feet long. Much over 6 feet and I've had them pile up on the water. That could be my casting, but...
If you need to know how to make a twisted leader, here's a link to the leader discussion. There's a video, and it's super easy. I make these simple leaders streamside, sitting on my tailgate, or even in the living room when the wife and cat are in bed.
The End of The Line; Discussions on Furlled & Knotted Leaders.
As for the advice about the distance, that's a great point. At that kind of distance, I've had quite a few bass jump, shake, spit out the fly, and I could swear they laughed at me as they swam off.