I live in a neighborhood that is culturally and racially diverse, in a city that's the same, and I simply don't think about it. Being respectful is part of who I am.
An example for me is the D&D games that went on around my dining table when Elderspawn was still in high school. There was such a cast of characters: a Muslim boy, a Hindu boy, a Russian agnostic, a Cuban-Irish boy, my Irish-Swedish kid, and an Italian kid with an allergy to Parmesan cheese, poor bugger. I'd make snacks for them, and it just never occurred to me until one kid mentioned it that I served things that were all halal, beef-free, and allergy safe. I called it being a halfway competent mom, personally. You just take everyone into consideration, and it works.
So, when I write, I just do the same thing. I don't care about skin color, or faith, or gender. It's all about people, and putting them in a setting that challenges them, and seeing how they deal with it.