You cant... (and comply with the law, anyway).
Legal tint here is 0 on windshield, and 0 on front driver and passenger. Well on the windshield, you are allowed whatever comes from the factory, and a strip along the top of the windshield... forget how big that strip can be but I havent seen anyone with just that strip on windshield tinted in quite a few years.
Any rear windows (such as behind b pillar drivers and passenger windows, and rear window glass), can be as dark as limo tint.
With that being said, I (and many many many MANY) others, choose to tint the front windows anyway. Windshield is touchier as the local law enforcement typically will get you for that, unless they cant see it (like my front window at 70% 3m crystalline).
I have 40% side windows (both front and back) and 30% back window.. but the back window is a different brand tint so they all basically appear the same % tint.