Gather soldering iron, solder, wire stripper, helping hands, heat-shrink tubing, and safety glasses
Unplug power and make sure the wires are not live
Slide heat-shrink tubing onto one wire before joining
Strip about 1/4 to 1/2 inch of insulation from each wire end
Twist the exposed wire strands together tightly
Heat the twisted joint with the soldering iron
Touch solder to the heated wire, not directly to the iron tip
Let solder flow through the joint until the strands are fully coated
Remove the solder first, then the iron
Hold the wires still until the solder cools and hardens
Inspect the joint for a smooth, shiny connection
Slide heat-shrink tubing over the joint and shrink it with heat
Use electrical tape if heat-shrink tubing is not available
Test the connection gently after it cools
Clean the iron tip after use and turn off the soldering iron