Anything but green or red (everyone's got one -- even me once)

Persoanlly I think silver works well with red interior

Dont let anyone pursuade you two tone is the way to go
Now I have to disagree on all counts ! Common or not, connaught green is fab. Indigo Blue with red leather is lovely. Also, my newly acquired car is in Jaguar Westminster Blue and I have yet to see a more regal and sophisticated hue, but I would say that !
Some two-tone works well - dark green with black wings for instance. Most don't though (not keen on that Ivory with Brown wings one).
Can't stand red, unless it's on an Aero.
And IMHO, silver doesn't work unless its on a Merc - Gullwing or SL190.
Not keen on black either.
And NO metallic paint finishes !
BTW, whoever owns that pink one in this months Miscellany should be shot at dawn for outrageously criminal acts to a fine English sports car !!!