[Aimok]

I have heard from a friend , that some Mainstream-Comics are colored with the help of prepared colour-palettes.

These are used by the colourists of a comic like these Image-COmics.
For example there should be a sunset, then there is a specific colour-palette which has "warm" colours etc.
And if u look at comics colored by different artists, this could be true...
Where can I find such Colour-palletes?

Hehe, this sounds like cheating, but I think if this is normally used, its okay to ask for it.

If its not usual, then I won`t ask...

[Kaiju]

Unless you work for a studio where they require you to use their palette (and I only think a few studios do that)... you make it up as you go. I know I do. There use to be a limit on the colors you could use, but with today's quality printing and paper that is no longer a problem. Do some research on color theory.

Choosing colors is the main part of being a colorist.

[quaternius]

umm...what kaiju said
plus - Painter comes with some color sets which might be useful. There are others on the internet. I have a skin-tones one on my site.
Good luck with your search.