Use VHT really good stuff just follow the guide below and it will come out great! this is from a month ago when i tinted my friends 2010 Jetta. Came out professional!
2000 Grain Sandpaper
Any can of clear coat
Microfiber non scratch cloth
Mcguires Rubbing Compoung
First take the 2000 grain sandpaper and wetsand the lights, occasionally wetting the sandpaper. You want to make sure the light is nice and smooth and no shinny spots. Keeping the light all dull will ensure the new paint will stick correctly.
Then tape off any areas you with to not be tinted, in this case i taped off the reverse light with blue painters tape. Then you want to make sure the lights are free of dirt.
Apply the vat night shades in a very light coat making sure to cover the whole area. It is absolutely important you do consistent light coats. Wait 5 minutes and apply another coat. On my WK i have 2 coats to be sure i won't be pulled over. But my girl (friend) didn't care about the darkness of the tint and just wanted it to blend in with the actual black base coat of the car so i applied 3 coats. After this step i waited a half hour. Don't worry if there are a few imperfections in the paint once the light has dried completely give it a very light sand.
Then its time for the clear coat. Clear coat give is that signature shine and protects the paint from any of the elements outside. For this car i applied 5 coats of clear coat each 5-10 minutes apart. The lights will end up looking like this if you do it right.
see how it has some very small bumps? we are going to wait for 12-24 hours for the paint to dry then give it a very light wet sane to remove any imperfections. Then thoroughly dry the light with a microfiber cloth.
The light will look dull, thats ok because now we are going to polish it which will make it look like glass
Take the mcguires rubbing compound and apply a good amount onto a microfiber cloth and start rubbing. You may have to apply some force to the lights to get them very shinny.
After that reinstall and you have perfect tinted tails!
Don't be scared because if you do make a mistake you can always sand it down and start over!