For me, I'm always a bit scared of mis-representing since I'm a white person, born and raised in Sweden. I think I've been more into representing women, queerness and different body types rather than race and have probably worked more with that than skin color.
However, in SPEJS, one of the human protagonists has a darker skin tone, because it really didn't matter what her skin tone was to the story, so why not? And besides, it's set in a sci-fi-setting far away in the future, so I thought I didn't have to care that much about nationality (more than "they're human"). So yeah, here are the two human protagonists (there are two more protags too, but they're non-humans, and I guess not relevant to this discussion):
What I'm trying to do is to avoid any stereotypes. They're just two awesome women kicking butt, you know? And I guess I'm not trying to mix in too much earth culture in it since the humans fled from earth 500 years ago, so they've probably built a new culture, and also mixed their culture with the one that exist on the planet they now live on.
I'm not sure if this is a good approach, and I don't feel super comfortable telling on how to work with this (since I only see it from a white scandinavian perspective), but I just wanted to show how I work with it in my comic. I think representation is great, and stories get more fun if there are more variations among characters, like skin tone, body type, sexuality etc =)