always mention the downsides of your ideas or approaches. people should understand the flaws of the current system.
understanding math:
know how to use machinery to transform problems into solutions
understand how to advance the field; learning to read and write proofs most people do not need to write proofs, but its important to understand how the real world relates to math
It's important to recognize a world in which you can phrase a problem and the ability to sovle a concrete problem within this framework.
read the wilson book for graph theory!