I'm also a starter in learning character design. So I know the struggle of designing a character that best match their personality and abilities. Having that said, I think I still have some starter insights that maybe you'll find useful.
For me, I have a distinct colour scheme for my characters. Because they are all in the same family, they all wear pink, wine red, gold and white in different clothing. After that, I also have my story set in a steampunk-ish post-apocalyptic world, where civilisation was slowly rebuilding itself, so I'm going for that old-fashioned Victorian era clothing but also adding enough features to the clothing so that it creates a sense of nuance from our actuality. I'll attach some of my design as examples:
So before doing character design, I think you would have to be very clear about the world and the characters. And take as much time as you want to perfect each design. At least for me when I was designing the protagonists of Dawnbreaker I had erased and redrew millions of times. The result might not be the best in someone else's eyes, but at least imo that's the way to make better characters. Hope you find it useful!