I use coolneon connectors to for the ends of my rope lights. They are inexpensive and they are polarized, which means they help you avoid connecting your rope light backwards (once you get the polarity right to begin with, that is). How much lead wire you need depends on how far your power supply is from the end of your rope light. On one end of the lead wire split it about 1/2" and strip about 1/8" of the insulation of each end.