Are there any books that were important to your development as an economist or that you would recommend to aspiring economists?
Capitalism and Freedom by Milton Friedman, Individualism and Economic Order by F.A. Hayek, anything by Ronald Coase.
What is the best (or worst) advice you ever got about becoming an economist?
Economics is very beautiful but if it is only beautiful, it's not worth doing because it isn't beautiful enough. It has to be useful for understanding the world. (That's a paraphrase from Milton Friedman...)