I've noticed on ref sheets, artists will insert a colour sample pallet like the one I have on page #2 of this posting. I myself had been using that method, but found out that sometimes you could click on an unnoticed lite or dark spot on the colour sample. I had finished a series of drawings to experiment with a slide show animation, and to experiment with the results of a new sound mixer I purchased two weeks ago. On those drawings, the colours are strayed off a bit but still not too bad...They can still be used in the upload I'll be posting in a day or two.
However...I found a way to catalog colours for characters where the colours can be consistent, plus any lighting and shading...That is the colours cataloged by code number instead of a pick-n-click sample. Colour pallets in Paint and Paint.net have numbers designated to to every colour and shading. By typing the numbers in on the pallets, the colour will be exact every time. I am going to keep a flashdrive of colour reference files like page #1 of this upload of my characters where the colours are by number rather than provided by a sample spot to click off of.
Shown below is how I got the colours off for my fursona (Moyo) and fiancée (Jamila) in a drawing I posted 4 years ago.
This Valentine's Day drawing below shows how the colours should be for my fursona and fiancée.
I am soon going to get a flashdrive to solely dedicate to colour reference files for all my characters, like page #1 is in this upload. When doing a drawing, a margin will be temporarily extended to the side of the page to copy and paste a reduced copy of the reference file so I can have the numbers to enter onto the colour pallet.
Included on that flashdrive will also be colour reference files for the cars my characters drive, the homes they live in, and other things that often appear in my drawings.