It's a pretty good mix overall, especially for a first try. Simple things to fix: the snare could be a little more forward/loud. I would either bring down the reverb on it or bring up the level. The backing vocals are too high in the mix, bring those down and then see where you are with the lead. You may need to bring the lead up, but it may be fixed by bringing the backups down.
The more difficult things for you to work on are going to be the toms and piano. The toms sounds very thin and the piano sounds artificial. Depending on how you recorded the drums, you may be able to eq the close mics better or use more tom mic/less OH. The piano is another deal. I'm not sure if that's a midi piano or just a line out signal from a keyboard, but try to figure something out to make it sound more natural. If its a keyboard with a midi out try using that with a plugin if you haven't already. If that's the most natural sounding signal you can record, try to get creative with the mix. Play the piano part through your monitors and record the signal with a condenser mic. This will give you a "room mic" signal that you can blend with the original. If you're not getting enough reverb on it, try pointing the mic at the wall opposite your monitors instead.
Please don't think I'm saying its a bad mix! It's very good for a first try. But it sounds like your looking for ways to improve it, so here you go. Remember, the best mixes are never done. Best of luck!
