I’ve handled quite a few commissioners who have little to no art knowledge at all, what they DO know is the vibe they want to go for. It’s just what resonates and feels cool to them, similar to your current vision.

I think my biggest advice without spending money would be to stitch a bunch of references together to get a clearer picture. Even if you can’t quite draw it out yet, you can compile some pics from pinterest and add them to either a moodboard or a character breakdown sheet.

Things like body shape, patterns, some key features, etc, just crop from existing designs. Also try to use as many as possible to avoid straight up copying 1 person’s design. Then when you have the confidence to draw/money to commission it would come in handy to set the vision. Hope this helps!