If you're looking to see if you're working with a live, dead, or leaking capacitor, this video is just what you need. You'll want to have a multimeter and you need to remember: capacitors can be dangerous things. They hold and release electricity very rapidly, so you can get shocked or electrocuted if you don't exercise caution.
A starter capacitor is used to start motors, and the easiest way to test a starter capacitor is with a multi-meter. Find out why any capacitor is a potentially dangerous device with help from an auto mechanic in this free video on auto part testing.