Before the Fire Starts
Preventing a grease fire is far more easy than starting one. If you are cooking with grease or oil, always maintain supervision of the liquid. Watch for warning signs like a change in smell or visible smoke vapors; Turn off the heat immediately if you notice them and remove the oil from the heat source if possible.
What Not to Do
If a grease fire does start, keep in mind these absolute "No"s before you act.
Never Use Water
If you've ever been in front of a pan of hot oil and accidentally put water inside of it, then you're at least passably familiar with the reasoning behind this rule. There may be a slight drop in the oil's temperature, but the water will pop as it heats and send the heated grease flying.
Never Move the Fire
Grease doesn't stop being a liquid once it's on fire. Trying to move it to a safer location can do more harm than good when the sloshing oil tips out of the pot and onto the floor.
Never Fan the Flames
You'll need more than a stiff wind to put out a grease fire. Fanning the flames will only make it worse.
What You Should Do
Turn off the Heat
Keeping the heat on will make the fire worse and potentially lead to other fires if you forget about turning it off in the chaos.
Smother the Fire
Remove oxygen from the fire to stifle the flames. Use a solid, tight-fitting metal lid for pots and pans. If some grease spills and stays ablaze, you can use baking soda to treat smaller problem spots.
Use a Chemical Extinguishing Agent
Grease fires are a Class B fire that can be put out by extinguishers rated for that class. If you use a common CO2 extinguisher, it may take more of the extinguisher's charge than a dry agent extinguisher.
Call the Fire Department If the Fire Spreads
If you feel like the fire has gotten beyond your control, you need to immediately call the fire department for the safety of your family and neighbors.