First, you have to go to traffic department and get a permit to install tint.It will cost QR20 only.
Recently I had my car installed a Llumar tint and it was amazing. Such a big difference compared when it was bare. It can control heat inside the car and best of all it has 5 years warranty.
They are located in Teyseer in Salwa road near the Group and Teyseer in New Rayyan after Education City.