I'm currently the technical guy and would love to learn how to also be the business guy - what do I need to do to develop those skills?

Getting your hands dirty is the best way to learn anyhting, so with technical topics, especially programming, I would just dive into projects and start coding, building things, and that's how I learned. In terms of business skills, what projects can I realistically undertake on my own that would help me develop those skills? Should I start a low-stakes business selling soap on Etsy or something? Is that adequate? Completely different ballgame from the corporate startup world - but would any of the skills from such a humble venture transfer to the larger stakes ones?

How might a technical guy become the business guy?