Not Logical
I've read somewhere about painting in grayscale and coloring with flats on top, using layer's blend modes to preserve luminance. It sounded very appealing to me! In fact, that's how I prefer to photograph. I set my cameras to desaturate the viewfinder and to save RAW files. As a result, I see only light and shadow when capturing, but have all the colors and can decide how to use them later.
With that in mind, I searched in my unfinished projects folder in Procreate and found the sketch you see here entitled "Mad Vulcan". The original photo was also there in a hidden layer.
Some hours later, I had the first final.
Just to be clear, this is not a portrait of a know Star Trek character. It's more like a cosplay self-portrait.
Final art. Green blood, more vivid colors, and some feathering on the hair to make the transition to the background smoother.
First final. Colors were applied as flats on blended layers. Vulcans have green blood and greenish skin, and it took a while to find the right color. Only after creating this page I realized that the blood injected areas should not be red.
Grayscale final. My plan was to paint an enraged Vulcan, but madness took over his expression, brush stroke by brush stroke. I just let him came to be and changed the title.
Following up on the idea, I traced the photo in a very quick pencil sketch. Bigger teeth and pointy ears were added, but that was all. The sketch remained abandoned in a Procreate folder for quite a while.
The initial idea of an angry Vulcan came from a selfie I took with ToonCamera for iOS. The app apply filters on the fly to make them look cartoonish like this.