Unfortunately, I'm not sure what you could do really. I guess don't have it in any steamy environments... keep it in a dry place as much as you can. I'd avoid having it in the kitchen when cooking, keeping it out of the bathroom at all times, and don't keep it in your shirt pocket when you're using the toilet... I've seen and heard of so many people dropping their phones in the toilet.
An ex co-worker of mine had a company phone with my former employer... dropped it in the toilet and flushed it on accident (I'm not sure how... exactly... but he wasn't that bright, so whatever). It's been referred to as the turd phone since, and it's still a running joke any time I see him around town.
If you are truly concerned about water damage, contact your local corporate Verizon store and talk to a rep about it and they can give you some pointers, I'm sure.
Edit: Also, try not to sweat on the phone... if the side of your face is wet, dry it off with your shirt. Common sense applies here regarding general hygeine...