You actually need to douse your device with the liquid, as well as the protector. Most first time installers don't use enough fluid and end up with bubbles and what not. I would not start with an iPad if you are going to do it yourself. To get a feel for the install I would start with something smaller like an iPhone.
I actually do my installs in a wet environment to get rid of as much lint as possible. First I turn everything off. I go into my small shower room and turn the water on full heat. I get condensation on everything because it becomes so humid. I then douse the protector and the iPad liberally with the installer liquid (which is just a minuscule amount of soap in water) - then do the install. I dry everything off with a microfiber cloth. I then let everything dry out overnight before turning the iPad back on.
I've done this for 1 iPad1, 2 iPad2, 1 iPad3, 1 iPad4, 1 iPad Mini Retina, 1 iPhone3, 2 iPhone4, 1 iPhone5 and haven't had any problems with liquid damage. I even returned the iPhone 5 because of the bad power button issue -
https://ssl.apple.com/support/iphone5-sleepwakebutton/ - and didn't have any problems with the return. And actually - the guy at the Apple store gave me back my Zagg cover - told me to take it over to the Zagg store - and get a new one installed. So I took the peeled off Zagg protector - over to the Zagg store and the guy - installed a new Protector right there.
Anyway - I like the HD screen protector - especially when I use something like an Adonit Jot - with a hard disk as the contact point. Depending on if you use a stylus and what kind - the protector may cause more friction than the plain screen. I haven't tried the thicker protector - and with Retina displays you want the HD version.
I don't recommend the full body protection. I've always had problems with the back coming off when using the same clear protector. I do like the leather skins for back protection though. They are much thicker and seem to last much longer.