If you spill liquid of any description on your computer, DO turn it off immediately, and go see a computer minded person ASAP. DON'T keep using it until it turns itself off.
If your pet gnaws a hole in your power adapter (or you've mishandled it, and managed to break open the casing or something), and said adapter starts arcing, DON'T continue to use this power adapter, and DO take it in to get looked at. Failing to do so may cause your hard drive to fail when an electrical surge travels up the charger and straight into the main logic board (and through that into the rest of your metal insides of your computer).
And finally, DO keep a backup of your data. You never know when the worst is going to happen and your computer is stolen/the hard drive dies/or any number of other things happen that cause you to lose use of your Hard Drive. But DON'T Keep your backup in the same place as your computer. Because if someone has stolen your computer/your laptop has been a victim of a lightning strike/Some disgruntled person decides to throw your laptop into the river, you don't want your only backup to have gone with it.
PS. With exception of the laptop into river, all of the above has happened to people who came into work in the past week.
PPS. Also don't use FileVault on your HDD. It will protect your data from everyone, even at the expense of the data - ie, even from you, should you need to get your data recovered.
PPPS. Take care of your stuff.