Huge Turn Off

Everyone knows that you should have, and should be able to easily reach, a fire extinguisher.
You should also know how, and be able to easily reach, the water shut off in your house. After fire, too much water is the second biggest sudden catastrophe that can happen. Neither are likely, but both are horrible and being able to stop either quickly is the key to reducing damage.
Once upon a time I took a civil engineering class that required us to calculate flow through pipes and head loss per foot and then design fire sprinkler systems to code. That was a long time ago and I don't want to do that again. So instead I just did a quick search and came up with a typical 1/2 inch pipe at a typical 50psi will flow somewhere around 15 gallons per minute. That's 3 five gallon buckets of water on your bathroom floor before your son even starts to explain why he sat on the sink and ripped it, and the valves, off the wall.
If you have well water, you have a breaker to throw to shut off the pump. Clearly label this. You probably also have a pressure accumulator tank and should have a valve at the exit that you need to turn off so it doesn't spray it's pressure reserve inside the house. If you have municipal water you have a master valve somewhere. Something that shuts off water to the whole house. Mine is in a box by my porch. Others may be inside the house. If you can't find it now, stop and think about how much water could be spraying around your house while you consider where it might be. The fire department will rush to help you if you have a fire. It's harder to get a plumber to rush for water. Just the way the world works. If you live in an apartment or a condo, I'm not sure if you'll have access to the valve yourself. If you don't, you should know who to call before you and the guy who lives below you have a very very bad day.
Being able to shut off the water is also the most elemental start to any plumbing job. You might not need to turn off the whole house to replace the faucet, but it's a good idea.
While searching around, I found this pdf - Principles of Supply Plumbing
It's the best simple book I've ever read on household plumbing theory. I would have done a few things differently when re-doing my house if I had read it before hand. I'm going to talk a bit about basic household pluming in the next few months. I'll start with the toilet. The throne. After all, you are the king.