Determine the depth required for buried electrical conduit in your area by contacting the local building authority.
Identify any buried electrical wires, gas or water lines by employing a locating service.
Hold one end of a chalk line at the start of the trench and have a friend hold the other end of the line at destination of the conduit. Pull the line tight and snap a chalk line along this route on the ground. Snapping a line is done by pulling it up under tension and releasing it so that it leaves a mark on the ground.
Dig a trench in a v-shape along the chalk line with a shovel. The v-shape minimizes the chances of the trench collapsing while working. Use a measuring tape to make sure the trench is deep enough for local building code.