The first thing you should do is clean the screen. Preferably using a real microfiber cloth designed for this kind of use and not a kitchen towl or toilet paper. Just make sure there’s nothing wet or sticky on the cloth, and even more importantly; nothing that will scratch the screen. Make sure you clean the entire screen carefully, and make sure you have a lot of light when doing so. You’d be surprised how clean and perfect a dirty screen looks in bad lighting. You can even use a flashlight when cleaning the screens, as that will really show you all the dirt you have to get rid of.
Next you have to make sure there’s no large particles on the screen. Large dust bits, hair and similar objects will make the screen protector bulge slightly and create air bubbles that no amount of squeegeeing will fix. Your best friend for this step is a can of aerosol dust remover which you can normally get in computer stores. This will let you blow away any leftover particles without any direct human interaction- dust often comes from humans after all.
When it’s time to apply the protector, be quick but careful so that you don’t get more dust particles on the screen while fiddling with the protector. No matter what you do, don’t remove the entire protective sheet from the screen protector before applying it, and do the whole thing upside down. that is, find the side normally market “1″ and pull off a few centimeters of the protective sheet while holding the screen protector with the 1-side facing down. That way, no dust will settle on the screen protector while you’re moving it around. Roll the protective sheet down alongside the screen protector so that you can hold both the screen protector and the end of the protective sheet in one hand and control both. Align the exposed end of the protector with the screen and make sure you have it perfectly aligned in all directions before pressing down. You should now have part of the screen protector on the screen while the rest is still protected by the protective sheet which is rolled between the screen protector and the screen.
The key to applying a screen protector is to roll it on, not lay it on. Air bubbles form because air is trapped between two parts of the screen protector that is in contact with the screen, sealing in the air. To avoid this you have to apply the screen protector only a few millimeters at a time. Bend the part of the screen protector that isn’t applied yet upwards about 45 degrees to create a curve where the loose part meets the applied part (but don’t fold it!) and then push the loose end of the screen protector down so the curved part “rolls” the screen protector on the screen. While doing this you also pull on the protective sheet to expose the screen protector as you go. This way you don’t have to deal with a giant sheet of exposed screen protector.
When you’ve successfully rolled the entire screen protector onto the screen, remove the second protective sheet. Use the same rolling motion as with the screen protector or you’ll end up creating air bubbles because you lift the screen protector up as you remove the protective sheet. Finally, use a squeegee (normally included with the protector) to smooth out any air bubbles that still made it in there. Using this method you can apply screen protectors much larger (and more successfully) than when using the “slap it on, see what happens” method that certain friends of mine seem to be fond of and if all goes right you shouldn’t notice that there is a screen protector there when you’re done. Good luck!
Credits on this article goes to Andreas Ødegård from nothingbuttablets.com