And remember to take the key out of the chuck before turning it on.
A kid in my high school metal shop forgot once, and the key punched a nice hole in the wall.
That reminds me of the guy who tried to protect his fingers from the pedestal grinder by using the sleeve of his hoodie instead of walking 20 feet to the tool room to get some gloves. His sleeve got caught at torn completely off. Fortunately he wasn't hurt and banned from the metal shop.
The drill press in the school shop had a large picture taped next to it of a guy with long hair that had half of it pulled out by a drill press.