At the end of the link below you'll find a BBC interview with Christie Watson, winner of this year's Costa Prize for best first novel, "Tiny Sunbirds Far Away."
The book is set in Nigeria and she talks about writing in the voice of a teen-age Nigerian (and finding the right voice to use), and using fiction to present issues about which you feel strongly.
http://www.bbc.co.uk/news/entertainment-arts-16587055
The video is six minutes long.
(How would would you like to have Mark Twain as your writing coach? Or how about Anton Chekhov or Jane Austen? You'll find their advice about writing in my newest book, "Your Creative Writing Masterclass," published by Nicholas Brealey and available from Amazon or your other favorite book seller.)