These are a few of the things that I have learned during my years in the animation industry. Always remember that you will be working closely with other people from various cultures and different ages (18-80). Not everyone will like the same things.
I always read and hear that your animation should be appealing, which means that the characters poses must be pleasing to view. But think about it, everything in your scene should be appealing. This includes lighting, colour, environments, props, effects and cinematography (composition, framing, camera moves and camera angles).
Many of these points are common sense. Some of them took me 10 years to learn.