Applying a screen protector is more along the lines of a fine art, than a process. Use the foggy bathroom trick when your first starting out. Install them for friends/family and what not. Eventually, the foggy bathroom isnt needed once your pretty quick at the application. Microfiber it, apply it, use a piece of tape (wrapped around your finger, inside out) to lift the corners to grab any dust particles...lay it back down, buff out bubbles...all done.
And like many have said, quality matters. Spend the extra. Power Support/SGP being the best. I also will use Switcheasy protectors as well, there clear rainbows a tiny bit, but not really dealbreakingly. Stay away from eBay, in my experience.
My 2 cents.