You're more likely to damage a laptop than a desktop PC (no one has ever driven off, forgetting the desktop on top of their car), and once damaged, laptops are harder and more expensive to repair.
Keep the battery cool. Today's lithium batteries wear out no matter what you do, but you can postpone the inevitable. Avoid heat and use the battery as little as possible. If you're going to be running on AC power for awhile, shut down or hibernate the computer, remove the battery, and work without it.
Be careful about eating and drinking. Spill coffee on your desktop keyboard, and you'll have to spend $15 on a generic replacement you can plug in yourself. Spill it on your laptop keyboard, and you could short out the motherboard. I'll admit that I use my laptop in cafes just like everyone else, but I put my tea as far from the electronics as my table allows.
When home, turn it into a desktop. You don't always need portability. When working at your desk, plug in a full-sized monitor, keyboard, and mouse. Not only does this get around the food and beverage problem discussed above, but it protects items far more valuable than your laptop--your arms, hands, and eyes. You can't set up a proper, ergonomic working environment with a small keyboard attached to a small monitor.
Find the right carrying case. Before taking it on the road, pack the laptop properly. Depending on your carrying preferences, look for a carrying case, backpack, or shoulder bag with a padded section designed especially for a laptop. (I use a backpack because the even distribution of weight is better for my spine.)
Clean the keyboard properly. When keys starts sticking, it's time for a cleaning. Shut down the PC. Keep it open as you turn it upside-down and very gently tap on the back so that crumbs fall out. Then use a can of compressed air (you can buy this at any computer store for a few dollars) to blow out whatever is still stuck. Be sure to read the instructions on the can, first. Then turn the PC upside-down and tap it gently again to get the last bits out.
Clean the screen when it needs it. If you can't see the email for the dirt, it's time to do a little cleaning. Start with a dry, microfiber cloth--the sort you get at an optometrist's office (you can also buy them at photo and computer stores). Move it in circular motions. Be gentle, but apply slight pressure on particularly stubborn spots.
If that doesn't clean the screen, make your own cleaning solution by mixing distilled water (make sure it's distilled) and white vinegar in equal proportions into a spray bottle. Turn off your laptop. Spray this mixture lightly onto the microfiber cloth, not onto the monitor. Wipe as described above, then wait ten minutes before booting up.
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