AA definitely does NOT need to be halfway, even as a "basic rule". No such thing. It all depends on its application. It needs to serve its purpose to smooth the jaggies and rough spots. But for this piece, following sporknife's advice would help a lot, as you have far too many colors and hardly any contrast.
The AA needs to have ALOT more contrast. Right now, it's just extra colors without doing anything. I won't say anything about proportions, cause obviously this is your style. Remember, the AA should be halfway (basic rule, i know about the 75 60 40 stuff) between the 2 shades you want to do. Like, if you have a green color and a black color, make a dark green color for AA. The shading on the left doesnt really need the aa though.
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