A fire blanket smothers a fire by cutting it off from the air. Using one well is mostly about hand position and about what happens after the blanket is down, and both of those are the parts that get left out of a one line instruction on a wall.
The sequence
Turn off the heat source first if the control is reachable without going over the fire. Pull both tapes sharply downward to release the blanket. Open it out and hold it with your hands wrapped in the top edge so the fabric shields them. Keeping the blanket between you and the fire, place it over the burning item from the near edge and lay it across rather than dropping it. Leave it alone.
Hand position is the whole technique
The single most common injury is to the backs of the hands, which pass directly over the flame if the blanket is held flat in front. Rolling the top edge over the hands puts fabric between the flame and the skin and forces the correct approach angle at the same time. This is the part worth practising rather than reading.
Leave it alone afterwards
The fire is out because the air is excluded, and the fuel underneath is still hot. Lifting the blanket to check restores the air and a pan of oil will relight immediately. It stays in place until everything under it is cold, which for a pan of oil means a long time, and in a commercial setting it means until somebody competent says otherwise.
When not to use one
If the fire is larger than the blanket, if it has spread beyond the original item, or if approaching it means crossing the fire. In any of those cases the blanket cannot exclude the air and the attempt costs the time that should have been spent leaving.
Questions people ask about how to use a fire blanket
How do fire blankets work on a pan of oil?
They exclude the air above the surface. The oil stops burning because there is no oxygen reaching it, and it then has to cool below its ignition temperature before the blanket can be moved.
Should the pan be moved after it is covered?
No. Moving a covered pan of hot oil risks spilling it and breaking the seal at the same time. It stays where it is.
Can a blanket be used on a person?
Larger blankets are rated for that. The instruction is to get the person to the ground and wrap rather than beat, and to keep the blanket away from the face.