>>34988970eyes are super tough to get right, especially if you're not drawing a neutral emotion
i usually try to go and screenshot similar enough expressions in the latest vod from a chuuba and use those as references
maybe it'd be better to develop an individual style, but i feel like depicting a chuuba really depends on what elements you take from the actual model
examples: the chuuba's mouth is positioned THIS far relative to her nose and chin and her mouth is THIS much wider than her chin, her side hair strands extend THIS far below her shoulders and cover the cheeks at THIS point, the top eyelids peak at about THIS far to the left, etc. etc.
hell when i started out doing art i usually measured facial features out with a ruler before learning to eyeball most of it. you don't need all of the facial features to be accurate but you want enough there to satisfy your conditions for "good"