The best way to learn how to become an entrepreneur is, of course, to just start. When you're forcing yourself to learn everything that's necessary to get a business idea up-and-running, you will learn different parts of both your specific business as well as entrepreneurship in general.

Aside from that, you can also work with other entrepreneurs. I find that roles that allow you to wear many hats, and work directly with founders and/or CEO's are best because it exposes you to as many parts of entrepreneurship as possible, and challenges you in many different ways quickly.

Now, for later-stage companies, a "different" type of entrepreneur is necessary. For this, I would try to work at later-stage startups (on the leadership team if you can) to learn the ropes on how things are done at scale and with a large organization.