I paint models for a living. A transparent red, allowing the silver to show through will be almost impossible to hand paint with a good results. The best approach would be to sand the area smooth, airbrush a similar silver (or whatever metallic is there), and then spray the red, feathering it to blend in, finally clear coat. Not an easy touch-up. If you really want to hand paint and the paint is just too thin, I would suggest several coats, allowing the paint to dry in between.
If you need help, I am available for hire.
-Astounding