How to make a skin or golden color in nail paint?
Skin color can be mixed if you have white, red, and yellow nail polish. Provided these colours have equal opacity and color strength, you can get a good idea of what the proportions should be here.
For a **gold coloured mixture** the process is the same, unless you need it to have the luster that is characteristic of gold. If you have silver or another metallic nail polish with such a specular effect, you could try adding yellow to it.
Another option is to combine several yellow hues. Looking at this picture:

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you can easily distinct three different hues (by eye, or using photoshop or a similar image editing tool), that can be mixed with the same three colours you would use to create the skin colour.
Uploading the image to an online colour palette creation tool, like coolors.co, you can extract the colors quicker and easier.