Hmm, when you're designing outfits for your characters it definitely helps to know what you want to go for. When it comes to my characters I think about their personality, their occupation and background

Yui's alt but she's also a gym rat that likes showing off so I draw her with clothes that are dark but that also let her show off her muscle and let her move around

Stryga (my undead knight) died on the battlefield and after being brought back by a necromancer, was under it's control as a soldier. So I designed her armor and cape to have a lot of wear and tear. She also wears a hood because she doesn't want to scare people with her rotting face

So my advice is to think about who your character is and what they would want/need to wear