Here’s an excellent knot for tying leaders to main line.
Cut off about 3 to 6 feet of leader material.
Place the tag end of the leader along side the main line so the two run parallel to each other for about 12 inches.
Grasp the tag end of the leader and main line in the palm of one hand, and with the other wrap the long end of the leader and tag end of the main line around the tag end of the leader and main line creating a loop.
Pass the long end of the leader and tag end of the main line through the loop twice.
Moisten and pull tight by first pulling on the main line and tag end of the leader with one hand, and the long end of the leader and tag end of the main line with the other.
The tag end is always the peace of line you’re going to cut off in the end.
Pull each of the four ends of the line separately to ensure the knot is tight, and then cut off the tag ends leaving about ¼ inches.