Squint at your image so you don’t see color (value has nothing to do with color, it’s how light or dark something is). Start with darkest darks and roughly paint them in. Work through about five values, from the darkest to the lightest.
You can infer some representation at this point but absolutely no detail. Use a tiny bit of dioxine purple to darken sienna for dark darks.
In this photo you can see how the image is already there even though I haven’t added any color.
If you get the values, you’ve got the painting. It doesn’t matter what the value of something is, as long as it is right in relationship to the value next to it.
