I'm a bit paranoid myself when it comes to working with electricity. What I do is throw the breaker, use a volt/multi meter to confirm the line is dead then I carefully disconnect the existing fixture w/o touching any of the bare wires. Before I put the replacement fixture on I rub the exposed wires together, just to make sure.
FYI, if you aren't sure which breaker works which light you can use a ******* circuit tracer: two 1500 watt space heaters or one heater and a hair dryer plugged into an outlet and turned on to throw the breaker.
FYI, if you aren't sure which breaker works which light you can use a ******* circuit tracer: two 1500 watt space heaters or one heater and a hair dryer plugged into an outlet and turned on to throw the breaker.