Nonfiction or fiction, if your story takes place in a real location, then you may want to consider linguistic fact-checking. This is especially true if you're writing about real world languages or dialects you're unfamiliar with (even if you're describing them in English), or writing characters that speak in different dialects.
You may not realize it, but everyone has language biases that can lead to stereotyping. You have biases about foreign languages based on your native language and the culture you grew up in, and you probably have biases about nonstandard dialects of English (or other languages) too, especially if you're highly educated. Many of these biases seem like fact, but are not scientifically or socially accurate. For example, did you know that there's no such thing as a language that is more complex, more difficult, more beautiful, or more logical than any other language? All of these are actually social judgments, and they often reflect unbalanced power dynamics across cultures. If you want your writing to accurately reflect the complex interaction between languages, make sure that what you're writing is fact and not assumption!
As an editor with an MA in Linguistics, I am specially equipped to help writers develop and refine the linguistic landscape of their story and its social consequences for their characters. I can also offer advice on how to accurately represent dialects and languages that you are not a native speaker of and provide broad-stroke sensitivity reading of linguistic issues (though I recommend hiring a native speaker of the language/dialect for more detailed sensitivity reading). I can offer initial advice and resources for accurately describing and integrating any language or dialect, though those with fewer accessible resources will require more prep time.
Pricing:
Linguistic Fact-checking: $35 per hour
Consultation on linguistic sensitivity: $45 per hour