1. Clamp one cable to the positive (+) terminal of the dead battery. Don't let the positive cable touch anything metal other than the battery terminals.
2. Connect the other end of the positive cable to the positive terminal of the good battery.
3. Connect one end of the negative (-) cable to the negative terminal of the good battery.
4. Connect the other end of the negative cable to metal on the engine block on the car with the dead battery. Don't connect it to the dead battery, carburetor, fuel lines or moving parts.
5. Stand back and start the car with the good battery.
6. Start the stalled car.
7. Remove the cables in reverse order.

Source: Wikibooks