I cant remember anywhere specifically that I used for research, I really just did searches for tinting forums, and different types of tint (ceramic, metallic, etc.). The sales guy was very helpful as well and had heat lamp type set-up that allowed you to feel the difference of different shades/types.
Seeing that you're in Houston I would definitely recommend the shop I used if your looking for a place. It was Executive Motorsports on Hillcroft and Voss. I called on Saturday morning hoping to set up an appointment and had shiny new tinted windows an hour later. The work itself took maybe 30 minutes. If you're a little bit more south I've heard rave reviews about Pablo Blue in Clear Lake.