Don't specialize. As Robert Heinlein famously stated, "specialization is for insects." Learn techniques in problem solving and design. Understand the various SDLC processes you may end up having to work in, around, or through. Learn how products are designed. Get a sense of how products are marketed. Read and learn how to affectively communicate. Network with and become connected to very very smart people who are passionate about design.
Ask questions. Be humble. Make mistakes.
Fail, successfully. Learn from your failures. Keep moving forward. Be empathetic. Compromise when it is appropriate, but stand by your principles. Analyze and gather evidence to inform what you design.
Never stop caring.