Everyone likes a little privacy, and for some people, the best place to get it is their car. But if your car has transparent windows, or you have a clear replacement window that sticks out, you won't get that privacy until you back seat.
First, ensure that the window tint kit you select is the right heat gun to shrink the tint for a tighter fit, but beyond that, you're done! Just let the windows sit for a while (remember the alternative transportation above?) and you'll have tinted windows on your car!