Tearing up your hands is almost a right of passage when it comes to CrossFit training. Check out pretty much any boxes Website and you'll see a lot of pictures of torn and bloody hands. Not pretty and not necessarily exciting for potential or new training partners to see!
You're going to encounter a WOD that is going to push you harder and farther that you ever expected and then it happens - that little callus you had on your hand turns into a blister and then tears! ARGH!?!?! Here comes that tape and the New Skin... for the next couple WODs at least.
So how do you avoid this? Well, you could wear gloves - but I don't want to go into that conversation right now. The other alternative is to maintain your hands so that the calluses you have don't creat friction points on your hands. There are a lot of sites that will help you keep your hands smooth and minimize the profile of the callus. Check out the results from a Google Search for some good info.
Another option is to change your grip. Cortney Seaman forwarded to me this article from the CrossFit Journal about how to change your grip to save your hands. It's well worth the few minutes it will take to read it.
BTW - with the heat and humidity hear in the Washington, DC area you are going to have WODs that mess with your hands. Do the best you can and don't tear up your hands if you can avoid it... there's nothing worse than brushing your teeth with your feet for a few days to convince you that it's time to take hand-care seriously!