Brainstorming is a really important step. It's a great opportunity for the team to get together and discuss any ideas they have. The best part is those ideas tend to new ideas once the team as a whole gets involved. It's a very organic process. After that, the key is to observe the world around you and incorporate those ideas into your designs. This keeps even the craziest creatures relateable. Finally, practice, practice, practice. It's a life long journey, full of it's share of twists and turns.