I got some window "defender" from Halfords on a roll. Wet the window withj spray from a spritzer, apply carefully and wipe out witha squeedgy. Quite easy if you take your time. It helps if you can remove the windows.
If diy isn't an option the yellow pages usually has window tinters in the car accessory , hi-fi, alarm section. They just do what I said above. But do it better!