I found my installer via some research on the newest iteration of Opticoat. While looking through the search results on google I was led to a discussion on the Tesla Forums, and came across a ton of great reviews for my soon to be installer. In the greater San Francisco Bay Area there are only two licensed installers for Opticoat (the company doesn't like to have multiple licenses in the small area).
I just did a very very brief search on Ziebart, and didn't notice a link for opticoat products, but they seem like they do good work, I'd suggest giving them a call and asking about it. As previously mentioned by Cesso, Cquartz is also a great product, so if Ziebart offers either one I'd say roll with it. I chose Opticoat because they have been around the longest and have a well documented track record of longevity and customer satisfaction, but Cquartz is a fine product and if it was all that was offered in my area I wouldn't feel bad about it for a second.
So yeah, I'd start with a call to Ziebart and ask if they do opticoat or cquartz, if not I'd ask if they know of a detailer that does. And make sure the detailer/installer is licensed by the company, otherwise you won't get warranty coverage!