try to get a place that will give you a lifetime warranty on it. also, depending on what car you drive, it would be a good idea to install some felt on the insides of your doors to prevent long-term scratching from where the windows roll down.

mirror tints are crap. try to get a charcoal color that doesnt contain any dyes. after aging in the sun, the dyes are what turns the color or you tint a nasty lookin purple or whatever other color it happens to be.

never heard of Ziebart. i went Llumar and its great. the films not too thick so you cant tell theres anything stuck to the inside of your window. also go to a dealer that electronically cuts out the window patterns. they should have a computer program w/ the exact specs of your windows to cut perfect patterns ensuring the best fit quality.

afterwards, never clean the inside of your windows w/ anything ammonia based. i use eagle1 auto glass cleaner which is safe for tints, or you can even just use some mild soap and water.