I was unimpressed with the screen protector that came with the Tilt2. It showed smudges and fingerprints very easily. I used mine until it was gross enough to change. After that I would recommend getting a high quality one like the brands you mentioned (Zagg, Bodyguardz). These brands come highly rated. And while they cost more than the cheapy "3 for $10" type you can get at Best Buy, its really not that much money based on the fact that it will easily last you 3-4 months or more if you take good care of your phone.
I bought a 3 pack from Boxwave, as they got some good comments on XDA. They are very well made, and don't smudge too easily. I got the "Crystal", although the "Anti-Glare" is supposed to be even better for not showing fingerprints (but has a matte finish, and a bit of texture which some people may like or dislike). Screen response is great (although I've never tried the touchscreen without a protector!). The one thing, the Boxwave Crystal shows a slight cloudy pattern in fluorescent light (nearly invisible when screen is on), which is not visible under incandescent or sunlight. Its a minor issue. But I might try Zagg or Bodyguardz next time. The Boxwave protectors also come with a microfiber cloth and applicator (a small plastic card you can use to press out the air bubbles).
Any quality screen protector will install with no air bubble, if done properly. You can almost always push any air bubbles to the edges to make them disappear using a credit card. The hardest part is installing so a minimum of dust is trapped under the protector. At a minimum, wipe the screen with a microfiber cloth to remove any fingerprints, smudges, and dust. Then use a can of compressed air (air duster) to blow any remaining dust off the screen. Quickly install the protector before any more dust drops on the screen.
You can also try a trick used by computer modders. Run a hot shower to steam up the bathroom for 10 minutes or so. The steam will pull a lot of dust out of the air. Then bring your phone, protector, and other materials (air duster, microfiber cloth) into the bathroom and do the install there. I've done this a couple times, and it works pretty good. Its really hard to get it perfect. But if you're careful, you will get satisfying results. I don't leave the phone in the bathroom while running the shower, as that might be enough moisture to damage the phone. A tiny bit of moisture may get under the protector from the steam. But this will disappear as the water evaporates.
A few other tips: Only handle the protector by the edges when installing. If you get a fingerprint on the underside, it will show forever. The better protectors seem to be much more forgiving with this. Try to handle as little as possible. It may take a few tries to get it lined up. But after that, don't mess with it. You may get a few specks of dust under the protector, and think you can fix it. But trust me, you will almost certainly do more harm than good. Just leave it alone. A few specks will not be noticeable when you use the phone.
Good luck!
