Whether it's to get you to work or just out for a drive, gas is a necessity. But how you go about filling the tank can make a huge difference in safety and how much gas you end up with. Using the right techniques and being careful can help prevent fires, explosions and spills, as well as keeping your vehicle running in top shape.
Before you touch the nozzle, make sure your car is turned off and all doors are locked. Gasoline tends to carry a static electric charge, and when you press the nozzle into your tank's opening, it can discharge that charge and ignite the gasoline vapor space. This can lead to a fire or an explosion in your vehicle or the gas can itself. To reduce the chance of this happening, always ground yourself by touching a metal surface before you begin pumping. This includes touching the nozzle handle, as well as the hose connector at the bottom of the nozzle.
Once you've touched a metal surface, remove the nozzle and replace the spout and vent cap (if applicable). When you're ready to fill your gas can, do it on a flat, open area of the station away from moving vehicles and people. Also, be sure to remove your can from your vehicle, since sitting it in the trunk or bed of a truck negates the grounding effect from the metal on your vehicle.
When you're done, return the nozzle and spout to the pump and collect your receipt if needed. Leaving the nozzle in your vehicle can contaminate it with dirt and sediment from the tank's underground storage facility that is stirred up by fuel trucks. This sediment can clog your car's filter, which could affect its performance and fuel economy.