Transparent paint is the magic ingredient for tinting lights, but there are a few words of caution to consider.
To tint tail lights, first remove the tail light housing. A phillips
screw driver or a special screw driver may be required. Paint the transparent housing on the side that is not exposed to the weather. (Optionally, if you are using a heat resistant paint, you can paint the tail light bulbs themselves. This would require less paint).
If the head lights have a glass shield, you can paint the shield on the side that is not exposed to the weather. In order to tint self contained housings such as halogen head lights, you'll need to use an outdoor all weather transparent paint, because you'll have to paint the outside of the head lights.
Words of caution. To be on the safe side, for safety's sake and not to get a ticket, do not paint any lights red on the front end of the vehicle.
Flashing blue signal lights may get you a ticket, also. Simulating the police could get you in a lot of trouble.
