Every so often you'll need to grapple with the dark arts, otherwise known as electricity. Given the reliability of modern motorcycles, chances are trials involving splicing wires and testing circuits will come only after you've done something silly, like hooking your iPhone charger to the turn-signal circuit.
As always, having the right tools will smooth your day and, as suggested, you won't really need to rob the hardware store to get going.
First on the shopping list is a multimeter. It's pretty easy shopping for these pups, because your needs likely will be modest. At the least, your multimeter should be able to measure DC voltage down to 100 millivolts and up to 500 volts. (Although you'll mainly be testing for 12 volts) It's should also measure resistance and current; our multimeter maximum current load is 10 amps, which is plenty. In other words, don't spend the big dough on a fancy multimeter. Also, while you're poking around at your local electronics store – that would be the D.I.Y. department in the local supermarket for the most of us – pick up an extra pair of multimeter test leads with alligator clips at the end. Most multimeter use standard 'banana plugs' where the leads fit in the instrument, so what's on the shelf will probably work on your meter.