(Reposted, for the last time hopefully.)
As always, when in doubt: Redraw from scratch, simplify shapes and lines, and make sure the undersketch is accurate. Especially when it comes to faces. It helps to not be so married to any one version or drawing of a character that you try to redraw it in exact detail, even moreso if it's a one-off sketch as opposed to a codified (and correct) design that's been refined by time and effort. And if still in doubt, sit on the drawing for a few days, a month, and then come back with fresh eyes to see what works and what doesn't. Basic editorial procedures.
Given that realistic rendering seems to not be my bag, I need to keep an eye open to doing simple and appealing at the outset of a drawing, as opposed to trying to pull a Moebius each time I do these stand alone illustrations. You'd think I'd have learned all of this by now. But I figure my mistakes are your gain, tens of viewers.