You will need some tools that most people who tinker with electricity will have.
Step 1: WARNING
For example, if you burn yourself with the soldering iron that is your fault. If you get lead poisoning from eating the lead solder this is you fault. If you burn down your house because you did not insulate your repair properly this is your fault. If your spouse whacks you with the rolling pin because you destroyed his/her Christmas lights guess what - your fault.
Step 2: Tools and Materials Required
Voltage Detector (see picture for example)
Heat Shrink Tube