I never installed screen protectors before, as I never had a device that needed it. However I had great success with mine, expect the first one, but now know the trick.
I used TechArmor High Defintion (HD) Clear Screen Protector. The pack comes with 2, and it's only 8-9$ US/Canadian, and comes with LifeTime Warranty, which I tried as I had to return my SUrface Pro 2 and order a new one. The company was nice to send me another 2 for free. So, thumbs up for that.
Anyway, the trick as is as follows:
-> Do the vacuum of your place to remove most of the dust that float in the air as you move. If you live in a house with central air, this might not be needed as central air filters the air for a lower dust environment than living in an apartment with standard heating/air conditioner.
-> It's easier to put the moment it's out of the box. If it's not, then you'll need to do your best to clean it as new. No streaks or dust must show when the device is off.
-> Take a shower. There is no point in this, beside making your bathroom humid to have dust particles fall down by the humidity and give you a clean room to work with. If you need to clean the counter top, do so before. Have everything prepares outside of your bathroom, ready to take once you are done with your shower. Do NOT have the device in your shower.
-> wear clean gloves. If by accident you touch the screen protector, it won't leaves marks which you won't be able to remove easily.
-> Starting from the top (where the camera is), peel the layer 1 (indicated in the screen protector film) by about ~1 inch (2cm), and apply it. There is no glue on the screen protector. It uses strong electrostatic. It will be like if there was a magnet. so you can remove and put again if you miss. You want t align everything centered. Make sure the alignment if perfect. If it's not, it will really show that you miss when you finish at the end. A 1 degree angle will feel exponential. So seek perfection. This is the most important stage.
-> Once you got it, peel off the rest of your the film layer 1. and let the film attach.
Once everything is in place. You will notice air bubbles. That is fine. Using the provided card and a nice micro fiber cloth (don't use the provided one, it's too small I find), push away the air bubbles.
You will now see smaller air bubbles. Those indicates that there is dust under the screen protector. using the provided 4 stickers. Use one to put it on the corner of the screen to peel off the screen protector, and the other as sticky tape to remove the dust particle which will be on the screen protector other device. As you lift the screen protect, expect some additional dust to show up. So it will be a small game of patience. But if you take your time, you should end up with no bubbles The second layer of the screen protector, is there to protect against scratches when you try to remove the dust and air bubbles. So if that scratches, don't worry. And no the screen protector wont' scratch as easily as the above layer protector.
Once you remove the Layer 2 protection on the screen film, you may have dust that comes back (hard to explain why, but when you'll do it you'll get), repeat the dust removal process. but it should not be as bad.
The company provides instruction videos on how to install the screen protector. You want to watch them before installing
iPhone Screen Protector | How to Install
And that's it. So it's really a small game of patience, especially is you seek perfection and having 0 bubbles.