I last year started using tippet rings (Amazon.com link here).
When a leader gets shorter and shorter throughout the day, you’re supposed to add tippet to it via blood knot. But, I’m not great at blood knots, and I’m particularly bad at them when I’m in a river. I’m too impatient.
I instead use a tippet ring. I find that the rings prolong a leader’s life (and, thereby reduces costs) and help me quickly add tippet and maximize time fishing.
When I do use pre-packaged leaders, I shorten them and add a tippet ring. Then, I add tippet to the ring. Rather than using blood knots, I use the Double Davy, which I find easier to tie.
When I use my go-to nymphing rig, I also use a tippet ring. When I’m running a tandem rig designed to run two flies at different levels in the water column, I’ll add about 22″ of tippet to the ring for my heavier anchor fly; then, I’ll add 8″ of tippet to the same ring and attach to that a fly that should ride higher in the water column. That’s usually something like a soft hackle, an emerger, or the WD-40.
If the water is shallow, like the Swift River, I still use a tippet ring, but attach the trailing fly to the anchor fly. Both flies are at the same water column level, as a result.
For my go-to dry fly rig, I add a little floatant to the tippet ring and parts of the leader. Good enough.
The video up top from Tightline Productions, one of the best video producers out there, has more on tippet rings.