I can't really help answer as to what brand of tint is best, but I can tell you to pick a shop based on quality of work, lifetime warranty and price. As to how dark to go, I would say 20% minimum... I went 5% and love it, but being that dark isn't for everyone. For the first week the windows are tinted, do not clean the windows or put them down... Doing so may interfere with the tint adhering to the glass.