I was reading a call for submission to anthology the other day. I do this from the small presses that I watch to see if:
a. The call for submission will spark an idea in my head for a story (I don't know why I do that; I'm busy enough, thank you)
b. I can, then, write something for their need.
This almost never works but when it does I usually hit on something good.
This last time got to write a short little piece that is very different from my usual stuff because it was written in the first person. I almost never write fantasy stories in the first person. But more importantly, the story relies heavily on the voice and tone of the narration.
The use of voice and tone is not an unfamiliar one to me. I first learned about it while writing poetry. My Last Duchess, by Robert Browning, is a perfect example. And I have some poems that rely on voice and that work well. But I've not used that technique in fiction, except perhaps, when written dialogue.
And as I think about it, first person stories work best when the voice and tone of the narrator matches the character that is speaking. That means you've really got to know that person well so you can write the narration the way he or she would. It requires close attention to the words used and the way thoughts are expressed.
For example, in my story, the narrator hates humans. He hates their smell and their taste and says so. I focus on these two senses because for the narrator these senses are the most important. To that end, the story opens with the narrator describing the joy she feels in the smell of her cave. The rich aroma of stone and gold mingling. And the cool air which she prefers to the hot wind driven by the sun outside.
So if you are writing in the first person spend some time with your narrator first. It will pay off in the end.