The basic styles of fishing swivels are designed for use in particular situations. Barrel swivels are used to connect one fishing line to another, such as a fishing line and leader. Snap swivels have an eye at one end for attaching the fishing line and a clasp at the other that connects to sinkers, lures and jigs. Three-way swivels have one eye to attach the fishing line, a second for a sinker and a third eye for a fishing leader. The improved clinch knot is the best all-around attachment to tie a swivel to a fishing line.
Hold the swivel between your thumb and forefinger with one eye of the swivel exposed. Insert the end of the fishing line into the eye. Pull about 8 inches of line through the eye as the tag end that is used to make the knot.
Wrap the tag end of the line over the fishing line five times, starting next to the eye and working away from the swivel. Wrap without creating tension on the line in order to form a loop near the eye of the swivel. Insert the tag end through the loop near the eye of the swivel and pull it through a few inches without tightening the knot. This will form a second loop atop the wraps you've made along the fishing line.
Make an additional wrap and insert the tag end through the loop atop the wraps. Pull the tag end until both loops close. Hold the tag end firmly and pull the swivel in the opposite direction to tighten the knot.
Cut the tag end about 1/16-inch from the knot using nail clippers or small scissors. Hold the fishing line in one hand and the swivel in the other. Pull the line and swivel in opposite directions to make sure the improved clinch knot is secure.