Guidelines

What and what not coloring

Stack Connections

Ideally, you don't want to color inner connections between parts, for example endcaps for fuel tanks, exception for inner part of shrouds(look at Vector's one, green/secondary), and for hatches

Inner Machinery

Would you ever spent your time painting something what would be never seen? So yeah, don't pain inner machinery, example for inner decoupler ring or TURD's MK2 docking module

Making Sense

Would you pain inner bell of engine? No? Because it is going melt away second you turn them on!

Overly dark areas

MK1-3 pod for example has these black fields nearby windows, and all. Exception is your perception and decorative stripes, like on fuel tanks, or like mk1-3pod "heatshield"

Textures

Variant Switches

I don't recommend using that for consistency, but you can if model has insane amount of different textures

Engines

All engines in ideal should have 3 switches: Mount(red main, green pistons, blue stripes/bottom), Engine(bell with main color, secondary "pipes" and blue additional details, but no machinery above bell), and Fairing(red outside, green inside, blue details).

Red, Green, Blue

Red for most area, green for second color or second most area, and blue for details or stripes if they exist

Formats

Save masks in Linear DXT5 .dds format. These are more performant

Misc

• If it has one texture switch, name Appearance, if more, Base, and Base is always first
• For the love of god, do NOT name shrouds SHROUD, name them FAIRING instead(im sowwy)
• If you need to remove TURD's false recoloring(like dart for example), use zzzzz_000_TU_Restock_000 instead of 000_TU_Restock_000, and zzzzz_999_TU_Restock_Recolour_000 for another one respectively, and add !MODULE[KSPTextureSwitch],* {} to Default file, check Dart for ex.

TLDR

Try to follow guidelines, but don't restrict yourself!

If you have no ideas, you can also look at stock's TURD recoloring

todo: add pic examples