YouTube is the best teacher here. I did mine using this video and a sequel:
https://www.youtube.com/watch?v=HnsbJO4MpDY&t=906s
There are all different methods out there; this is the most DIY one I found, but you can find videos by guys who do this as a paid service showing how they do it.
The hardest part for all the methods is that you really will have to paint the characters by hand; there's no "roller" method that works reliably on banged-up old plates.