What is a good rule to follow when using a fire extinguisher?

When using a fire extinguisher, aiming at the base of the fire is essential because that is where the fuel source is located. By targeting the base, you are directly attacking the origin of the flames, which is crucial for extinguishing the fire effectively. This approach helps to smother the fire and cut off its oxygen supply, leading to a more successful outcome in controlling or extinguishing the flames.

Using a fire extinguisher poorly, such as aiming at the top of the fire, may only push the flames away momentarily without effectively addressing the source of the fire. The other options may also mislead users in different regards: maintaining a safe distance is important, but it's crucial to ensure that you can still reach the base of the fire; and while it's wise to use an extinguisher primarily for small fires, the technique of aiming is fundamental to all applications.