San Diego Jam Knot. I use this all the time for all sorts of stuff. Highly recommended.
One thing you can’t buy is a good knot. You have to tie it on your own. And while no single knot satisfies every angling situation, mastering a set of the best, one in each of four major categories (terminal knots, line-to-line splices, light-to-heavy line splices, and terminal loop knots), will reduce break-offs and have you fishing more and retying line less. These four knots are the strongest in each category (see "additional info" below for details on how we tested them).
The Strongest Terminal Knot (for tying on a lure or fly)
The Winner: Six-turn San Diego jam: 94%
Palomar knot: 91%
Five-turn double clinch (or Trilene knot): 87%
Five-turn improved clinch: 86%
The Skinny: Because the San Diego jam uses wraps around both the tag end and standing line, the knot has a better cushion and is stronger than clinch knots, which wrap only one strand. The improved clinch owes its popularity to its old age: It was one of the first knots that worked well with monofilament line, a WWII-era invention. Knots have since advanced -- time to learn the San Diego. (Tied to a size 3 Berkley Cross-Lok snap in tests.)
1. Thread the line through the hook eye and double it back 10 inches.
2. Wrap the tag end over itself and the standing line six times, moving toward the hook.
3. Pass the tag end through the first open loop at the hook eye.
4. Thread the tag end through the open loop at the top of the knot.
5. Lubricate and tighten by pulling the tag end and standing line, making sure the coils stay in a spiral and don’t overlap.
Photo by Pete Sucheski