I am working on a Enterprise Refit model, one thing I am hung up on is the color of the hull. Was the refit mostly white? I was reading on a hobby forum that the color used on TMP was actually a pearl type paint, which was actually dulled in the movies II - VI. I am trying to create as close to TMP Enterprise as I can, or as close as I can get through simple air brushing.
I guess if you really want to get as close as possible, do the crazy TMP (as close as possible) pearlescent colours (there is a myriad of colours on her), and then ruin her, I mean give it a light dull coat and that'll mute all those colours. The other big difference is that there was a lot of green on TMPs Enterprise (the back and around the deflector), and that was changed to blue eventually. That would be a big difference. have fun!
There's also the real-life and appearance considerations. You can opt for the paint scheme as used directly on TMP ship model. That would be accurate. Then there's the appearance it had in the film, which was greatly affected by studio lighting effects and camera work and all that. Some might want to achieve, as close as possible, the look of the film. That look went beyond just a paint job. So you gotta weigh your own factors and preferences.