To me, skinning is like art. If you want to improve, try learning from your favorite skins someone else has made... Then develop your own style once you've gotten the hang of it. I'm definitely not adequate to be a mentor, but that's just some advice.
The oceans in mc are similar to the ocean in Wind Waker: Plenty of water, not enough action. I know people already said this, but it would be cool if they added aquatic mobs. Also, actual tv's? They turn on when you connect redstone to them. Seasons (following real time) would be awesome too.