Go for it! It's great practice for learning to stalk fish and make accurate casts and specific presentations. When you hook up you'll get some practice with clearing the line and fighting a fish off the reel. Just wait 'til you hear that reel scream! Oh yeah, and watch your knuckles
Ditto Matt's comment about the heavier line. Even if it's a small pool with no snags you'll need the heavier line just to get the fish in hand and remove the fly. Just make sure that your leader or tippet is still the weakest link in your set-up or you may risk losing your fly line. I've been using 20# fluorocarbon for a leader (no taper, no tippet) because there are some thick weeds in the places where I fish and the water is somewhat murky. It may seem like overkill, but the fish quickly popped the knot every time I tried to use 12# fluoro. I've now learned a better knot and will try again with the 12#. (Gotta use the Uni Knot with this stuff, not the Improved Clinch Knot).
Go get 'em -- you won't be disappointed!