Most electrical wiring jobs are relatively easy to handle with a few inexpensive tools. If you want to do fairly sophisticated repairs, you'll also want a multi-meter.

Circuit tester
Simple and inexpensive, a circuit tester plugs into a conventional outlet and tells you whether the circuit is "hot" (charged) or properly grounded. You can buy a circuit tester here.

Continuity tester
A small, battery-operated continuity tester costs less than $10. It can be used to determine whether wiring is broken and electrical circuits are complete. You can buy a continuity tester here.

Lineman's pliers
A pair of these is the best tool to use for cutting heavy wire or cable and twisting wire ends together. To twist two wires together, hold them side by side with one hand, their stripped ends aligned, and point the blunt end of the pliers in line with them, clamp down, and twist in a clockwise direction. You can buy lineman's pliers here.

Long-nose pliers
Long-nose pliers are great for bending small loops at wire ends or for cutting off wires (most include a wire-cutting section). Use the pointed end of the pliers to form a smooth, 3/4 circle at a wire's end, designed to circle around a screw terminal (always hook the wire onto the terminal with the end of the bend sweeping clockwise from the wire). You can buy long-nose pliers here.

Multi-meter
You'll want to have a multi-meter on hand for making a variety of continuity checks, checking voltage, and other similar tasks. Read the manufacturer's instructions for a thorough understanding of techniques. Multi-meters, which do the job of ohm meters, volt meters, and related tools, are sold at consumer-electronics stores for under $20. You can buy a multi-meter here.

Neon voltage tester
This helpful little tool can tell you whether wires are "hot" or not. When using it, be sure to hold only the insulated probes, not the bare parts. Touch one probe to what you suspect is a hot wire and the other probe to a neutral wire or grounding wire (or grounded metal electrical box). If the small light glows, the circuit is live. You can buy a voltage tester here.

Screwdrivers
You'll want an assortment of screwdrivers with insulated rubber grips. Be sure to get both flat-bladed and Phillips-head drivers. You can buy screwdrivers here.

Wire stripper
Most electrical wires run inside a sheath of insulation—a plastic, rubber, or paper coating that prevents bare conductors from shorting against each other or shocking you. When splicing wires or connecting them to devices, you must remove the insulation, a relatively simple job when you have an inexpensive wire stripper. The stripper should be set so that it cuts the insulation but doesn't nick the wire (use the slot that matches the wire conductor's size). You can buy a wire-stripping tool here.