This guide has been amended since the original post to illustrate techniques I've used successfully over many PDAs and phones, and each time I get a PERFECT install, no dust or bubbles and almost always perfectly even edge-to-edge positioning.
I can STRONGLY recommend the WriteShield Crystal from Pocket PC Techs, the Vikuiti films which are made by 3M or the SPG/Spigen/Steinheil screen protector products. What I find different about these two brands is that they seem to have a harder more scuff/scratch resistant surface than low-quality 'cheapo' sheets. I had a WriteShield on my HD2 for over a year without ever noticing any damage to it.
Based on some comments offered later in this thread, I'd like to interject some thoughts by way of personal commentary.
There seems to be some bizarre belief among some XDA members who consider spending the least amount of money they can get away with on a screen protector to be some sort of badge of honor, as though saving $5 on an item that protects a $400++ phone is a laudable goal. Make no mistake about it - just because you may have paid only $50 for the phone doesn't mean that's what it's actually worth. Perspective, folks. Perspective. I've used all sorts of sheets from Boxwave and Fellowes, and none of the 'cheapo' types can hold a candle to the products I advocate for above. I'm not a plastics or chemical engineer, but there is a difference from one sheet to the other. The point about buying a better protector is that you'll have to replace it less often, if at all. In my view, any item that keeps my (very expensive) phone looking newer for longer and thus preserving my pleasure and ease-of-use is worth a few bucks. [Thanks to ephestione for prompting me to discuss this!]
Now, on to the procedure.
** Note: This guide is intended for self-adhesive (non-water based) films, but the techniques should work for those other types like Zagg which rely on a spray method. Some may also wish to use a mild soapy solution and/or diluted isopropyl alcohol to help reduce static and ease positioning, but I caution strongly (and would go so far as to discourage it) as excess can seep into the phone and damage it. It also will make any dust particles hard to see and even harder to remove.[Props to frottage and jmwarren85]**
- A clear, clean, well lit work area. (An environment with higher humidity like a bathroom where you've run hot water in the shower can help eliminate static that can attract dust) [Thanks, RammY]
- Adjustable height chair to get comfortably close to the phone without straining (I recommend roughly chest height, so that you can easily rest your arms on the work surface).
- Sheet of paper or cloth to prevent scratches to phone and to present a clean work area.
- Screen protector of your choice (see recommendations above).
- Lint-free cleaning cloth, either felt or microfiber. I don't recommend toilet tissue (lint residue). Some paper towels are alright, but rough until the fibers soften up, so be sure you allow them to get damp.
- Scotch (or other brand of clear) tape. Try not to use tape with very strong adhesive such as clear packing tape or "duck" tape, as it will be harder to remove at the end of the procedure.
- Low-tack (not very sticky) tape such as painter's tape or masking tape - something easily removable.
- Cleaning solution such as Windex, or better yet, anything suitable for optics or eyeglasses. What you want is something that won't leave a residue.
- Reading glasses, for those of us over 40.
Before you do anything, take a moment to lay the screen protector on top of your phone and move it around a bit to examine how much room you have on the edges. This will give you a sense of how much 'wiggle room' you have and how close on any one edge you'll have to get when doing the actual install. Some protectors are cut with closer tolerances than others. This step will enable you to have a sense of spacing so that you can more closely lay the sheet down with even spacing on all sides.
Also, make a note of the cuts and shapes. For example, the Inspire 4G has a different radius at the top and bottom corners, and the screen protector is cut accordingly. Note what happens in these two shots when I flip the protector in the opposite direction:
- Once you've sized up your screen protector layout against the target, prepare two strips of "scotch" (clear adhesive) tape about 1"-2" long each, folding both sides side over to stick it to itself as a 'flap' or 'tabs', which will give you an easy way to grab the tape for removal after the screen protector is deposited onto the phone.
- Many screen protectors already have 'tabs' pre-installed. If your product has existing 'flaps' to help remove the protective coverings, the above step is not necessary.
- Note: On some larger devices such as tablets, and in certain cases even on smaller phones, using more than 2 tabs can be an aid. Use your judgment. The beauty of this is that you can experiment with the feel of handling the protector prior to application to get some practice,[Props to igalan]
- Lay one on the edge from where you will be removing the film backing on the adhesive side of the screen protector if your product does not already have one. Do the same for the top if your product has an upper protective layer but no 'tab' to remove it.
Clean the phone thoroughly. This is where the lint-free cloth and cleaning solution come into play. Be sure that you've removed all the fingerprints and dust specks. Use the condensation from your breath to see any flaws or residue left on the screen. Often it helps to buff the area when dry. It all depends on whether the residue you're cleaning is greasy, sticky, or whatever. Some smudges respond better to one method than the other.
4/28/13: Post amended to reflect lessons learned and improvements to technique using my HTC One as the model.
- Lay phone on flat, clean surface and apply low-tack (masking/painter's) tape to the long side of the phone on the back.
- Press tape to ensure it sticks around the sides as you bring it around to be even with the top surface.
- Position screen protector as desired, and using one hand then the other, press tape on top of the sheet. This will act as a 'hinge' to anchor the protector in position as you proceed through the next steps.
- Lift screen protector up and clean phone screen thoroughly again just to be certain, to ensure there's no dust visible.
- Holding the one tape 'handle' that you created near the tab, remove the backing from the protector. You're going to get static electricity from this. I've never seen a case where it didn't happen, so be prepared for it, and do your best to keep the protector far enough away from other objects in the area it might come into contact with.
- Once you've successfully removed the backing, grab the 'handle' opposite the taped side and SLOWLY approach the phone with a 'squeegee' or credit card, pushing the air out. Use your finger if necessary to help keep the product flat as it lays down and adheres to the phone's screen.
If you've been lucky enough to be in a dust-free environment, and slowly applied the protector from one edge to the other, you should now have a perfectly installed screen film. However, most of us are not that fortunate. This is again where the scotch tape 'handles' come into play.
** NOTE: This technique is NOT recommended for glass screen protectors, because of the "apply once" type of adhesive used. **
- Create a 3rd length of scotch tape, but this time, only fold it over on one edge, which is where you'll be handling it, and hold it with one hand adhesive side up. This segment of tape will be the 'mop' used to remove any residue.
- Find the spot that has the dust specks on it. Because any dust particles will have almost certainly stuck to the backing of the protector, as you pull up on one of the remaining 'handles' that are still attached to the phone, the dust specks will adhere to the protector, rather than the screen.
- Note: Some very fine dust particles or fibers can lift the protector from the screen surface just enough so that they'll appear as though they're air bubbles. If you're concerned, follow this procedure and be prepared with a 'mop' to address it.[Thanks, MuF123]
- Slide the strip with your other hand to the spot where the dust speck is, and let the film fall down again so that the tape comes into contact with the adhesive, and LIGHTLY apply pressure.
- Lift the protector up, peel the 'mop' away and it should take the dust speck with it. Repeat as necessary.
- Presuming all went well, you have no dust under your screen at this point. Remove the tape flap you made starting from the center of the screen and peeling back to the edges, rather than from the edges inward which would risk lifting the protector off the display.
- HINT: Do not lift the tape at a 90-degree angle to the surface of the screen. See if you can pull it off as parallel to the surface as possible, which again will reduce the risk you'll pull the protector off the surface of the display.
- If there are any air bubbles, they should be close to the edges, easy enough to push out using your finger or a credit card covered with your cleaning cloth to prevent any grit from the card from scratching the protector.
Hope this helps!