How to Care for Your Mac OS X with Snow Leopard

Mac OS X Snow Leopard is a resilient operating system, but it isn't impenetrable. There are some things you should do to protect your Mac from bad things, like OS instability. Here’s a list of Mac do's and don'ts:

* Don't unplug your Mac when it's turned on: Very bad things can happen, such as having your operating system break.
* Don't use your Mac when lightning is near: Here's a simple life equation for you: Mac + lightning = dead Mac. Oh, and don't place much faith in inexpensive surge protectors. A good jolt of lightning will fry the surge protector right along with your computer as well as possibly frying your modem, printer, and anything else plugged into it. Some surge protectors can withstand most lightning strikes, but those warriors aren't the cheapies that you buy at your local computer emporium. Unplugging your Mac from the wall during electrical storms is safer and less expensive. (Don't forget to unplug your external modem, network hubs, printers, and other hardware that plugs into the wall, as well; lightning can fry them, too.)
* Don't jostle, bump, shake, kick, throw, dribble, or punt your Mac, especially while it's running. Your Mac contains a hard drive that spins at 4,200 revolutions per minute (rpm) or more. A jolt to a hard drive while it's reading or writing a file can cause the head to crash into the disk, which can render many — or all — files on it unrecoverable. Ouch!
* Don't forget to back up your data: If the stuff on your hard drive means anything to you, you must back it up. Not maybe, must. Even if your most important file is your last saved game of Call of Duty 2, you still need to realize how important it is to back up your files. Fortunately, Mac OS X Snow Leopard includes an awesome backup utility called Time Machine. (Unfortunately, you need either an external hard drive or an Apple Time Capsule device to take advantage of it.)
* Don't kiss your monitor while wearing stuff on your lips: For obvious reasons! Use a soft cloth and/or OmniCleanz display cleaning solution to clean your display.

Reff:http://www.dummies.com/how-to/content/how-to-care-for-your-mac-os-x-with-snow-leopard.html