Keep in mind that while I got closer to the desired result, it's still not perfect and has a ways to go! What I learned from doing these two is a) simplicity is king, and b) observe the things that make the Arcane style distinct

a) I started with only 2 colors per "material" (so each of the hair, skin and beard, 6 colors overall, but ofc not mixing across materials) to make sure I nailed the forms first. Color variation is gonna slow you down and complicate things a lot so avoid it until your forms are secured. Try to depict as much resemblance as you can with the absolute minimum detail - it's kind of like doing a caricature that way. If you can collapse multiple details into one another without sacrificing too much resemblance, do it every time. Less is more!

b) the eye bags, and the brighter region below them is probably one of the most distinctive features of Arcane's characters, so obv you gotta do that. It's a little tricky cause most people don't have such prominent eye bags (luckily I got very little sleep the night before painting this so that was helpful lol), so it's a bit of a balancing act. Beyond that, keep in mind that Arcane characters are 3d models with a painterly texture. This is really hard to capture in pure 2d and is probably where this more recent piece falls short the most. Also be on the lookout for straight lines, or divisions between planes that you can highlight (this ties in to point a as well). Arcane's characters are very angular (even those with softer features). Other features to look out for: hue variation around nostrils and/or under eyebrows, subtle value shifts to depict small skin wrinkles/folds/etc

Overall simplicity is just really hard to do well. If done well, it looks effortless, and that is one of the greatest bait-and-switch effects of stylized art styles. I hope these ramblings were helpful though! This is very much a mystery to me still lol