Screen cleaning.
1-Dilute isopropyl alcohol (not rubbing alcohol, as it may contain oil) into a solution of no greater than 50% alcohol and 50% with distilled water / deionised water.
2-Put the solution in a small atomiser bottle, the type that you push from the top to get a fine mist. It works really well at getting just the right amount on your screen with a spray on each quadrant.
3-Apply the solution to a cotton cloth, such as an old T-shirt, lint-free microfiber cloth, or other very soft cloth. A large cloth is best, since it will help to reduce the risk of leaving streaks across the screen from finger pressure.
4-Wipe the cloth against the screen in a counter-clockwise, or other consistent motion. Apply an even pressure to the cloth but take care not to press your fingers into the cloth or screen.
Tips
1-Expensive store-bought products contain the same mixture of alcohol and water. Others include Ethylene Glycol. You really do not need all these additions, which may be harmful to your health and that of the environment.
2-If you apply too much of the solution and it is drippy or too damp, wipe it off with a soft cloth and apply less.
3-Tissues will likely leave flakes of paper on your monitor. It's better to not even try using them.
4-You don't want mineral spots on your screen, so don't use tap water.
5-Using a 100% cotton cloth or shirt alone, without the alcohol mix, can sometimes produce the same smudge-free results without going to the trouble of mixing your own solution.
6-If you're a photographer, you can use your lint-free lens wipes instead of a soft cotton cloth.
7-If you are looking for a cheap way to get your hands on ready-made cleaning solution, try CD/DVD cleaner, which is often 55% Isopropyl alcohol and is not harmful to most plastic surfaces.
8-Lint free cotton cloth will work best.
8-If you are the owner of a lacquered instrument you can use a dry polishing cloth. You have to use a bit more force with dried on spots, but with smudges it works just fine.
Warnings
1-NEVER drink Isopyopyl alcohol.
2-Do not use cheap paper towels. You will scratch the LCD screen.
3-Avoid using products such as Windex because these contain ammonia and it can degrade the LCD panel.
4-Shut down your laptop, unplug it from the power adapter, and remove the battery before cleaning it or you risk damaging the laptop.
5-If in doubt, test a small area of screen first.