For me, I only like customizing MC and LI, and I hate having to customize family members. It just takes forever and I really don’t care how they look.
I find it really helpful to have some kind of brief description of who the person is and any personality traits or back-story details that might affect/be affected by what they look like. For example, “This is your main love interest - he’s the strong, silent type and comes from a working-class family.” (Maybe it’s just me but there are some hairstyles I can only see on rich people!)
And if you limit any customization options, it’s helpful to say why. I remember one story only let me choose certain weird hair colors and never said why and then the hair color never seemed to play any role in the story and I was just going “WHYYYY did I have to use this dumb color?” the whole time. I think it was to match the art scenes, which frankly I don’t care about so I wished they had just put a warning that if you don’t choose X hair/skin colors it won’t match the art. Cause then I could decide if that matters to me or not.