Locate the simple conductors. These will be easy to identify, as they simply display in the form of a line. If wires connect lines together, you will see a dot at the intersection. If no wires connect the lines, you will see a bridge in the intersection rather than a dot.
Locate switches. Switches would allow a user to break a circuit in case of a broken wire. A switch can be found by looking for a line that contains a raised platform. This looks like a bridge that has been raised. The line will be disconnected at the point of a switch.
Find resistors. They resist the flow of any charge. You can find a resistor by looking for a jagged line.
Find non-standard components in the key. If the specific diagram you look at contains a key, simply read the key to figure out what the specific symbols detail. Further, you can find text in the diagram to break down voltages and other characteristics deemed important by the creator.