What do I need before doing my own electrical work?
Three things, knowledge, tools, and time. Most important of these is the knowledge of how to safely work around electrical equipment. This includes, but is not limited to, understanding how to correctly de-energize and test circuits before beginning work. Also, proper techniques are imperative when stripping, splicing, and terminating conductors as well as installing electrical wiring and devices. There are a number of DIY'er books available that help illustrate these points.
Also needed is at least a basic understanding of the circuits being worked with. This can be gained through books, experience and the friendly folks on the Electrical Wiring Forum.
Finally, the knowledge of proper tool use and selection is a must. Some tools such as multi-meters take some time and practice to utilitze properly.
The tools required can vary from nothing more than a tester, a screwdriver and a pair of wire strippers for replacing a receptacle all the way up to a truckload of tools and equipment to wire an entire home. At the very least an electrical tool kit should include the following for simple replacement of switches or receptacles:
Tester: The most important tool and imperative in testing for properly de-energized circuits and useful for trouble-shooting problems. These can vary from simple testers that use a neon light or incandescent bulb up to solenoid testers (Wiggys) and multi-meters. Regardless of the tester used it is important to understand how to use it when verifying that circuits are de-energized. Non-contact voltage testers, while very useful, should not be used as the only means of testing a circuit for safety.
Screwdrivers: An assortment of Phillips and flat-bladed screwdrivers should be adequate, however with Robertson (square recess) screws becoming more popular, a Robertson driver can be useful at times.
Pliers and cutters: At least a pair of linesman's pliers (8" or 9"), needle-nosed pliers, and diagonal cutters (dikes). Also useful are pliers with built-in crimpers.
Wire strippers: A good pair of strippers will cleanly remove the insulation from wires with a minimum of effort and without nicking or damaging the conductors. Although more expensive doesn't always equate to better quality, the cheap $2.95 strippers that can be found in some stores should be avoided. A good pair will usually run $10-$12 and up.
Of course even if armed with knowledge and the best tools, it takes time to do any job properly. From the standpoints of safety and reliability, attention to detail is vitally important when performing electrical work. Always budget plenty of time to perform tasks and if an unexpected situation is encountered don't guess at the right solution . . . take the time to find out the correct answer.
Be sure to check the main FAQ page for other topics related to safety, tool selection, and tool use.
Thanks to Sangan, Mizzou_KX, Normel, DavidR and Tom_O for their help on this topic.