Oh yeah. I'm doing it. In first person. Something I keep seeing in current YA lit and can't stand. Why? Because it's confusing. The characters always end up sounding the same, which is espcecially annoying when one is supposed to be a boy and they both sound like girls. After reading quite a few of these, I think I've come up with some ways to avoid the pitfalls, and I want to try my hand at it.
#1: Catch Phrases
The characters I've chosen to narrate are very different, which I think, helps. My male MC is a Southern boy, so he narrates with Southern comparisons, ie, "She looked like a long-tailed cat in a room full of rocking chairs." Often I start his chapters with one of these sayings so the reader knows right away who is speaking.
Okay, this is similar to the above, but the way two people describe things should be different. My female MC is VERY detailed. Where my male MC would say, "her eyes were blue," she would say, "his eyes were pale blue with flecks of green and gold slashing through the iris." Again, if I start a chapter with a saying like this, it establishes who is speaking.
I also keep the voice consistent throughout the chapter, and when writing my male MC's parts, stop myself when I catch him describing clothes. Boys don't care about clothes like girls do (at least not most of the boys I know.) If he says something about clothes it might be, "She was wearing those huge heels that every girl at school tromps around in."
This is such as easy way to establish narrator at the beginning of a chapter...say the other character's name. "John!" I cried.
Obviously my female MC is speaking because people don't go around shouting their own names out (most of the time).
These are my tricks for making the perspective switch a little easier for the reader. Have you ever written a novel from two different narrators in 1st person? How did it go? And what did you do to make it clear to the reader who was narrating?