When I was in college I read The Passionate Programmer by Chad Fowler, which was my first exposure to the concept of treating yourself as business even when working for an employer.
Later on a found Patrick Mckenzie's blog, via his blog post on salary negotiation. https://www.kalzumeus.com/2012/01/23/salary-negotiation/ Which lead me to discovering a bunch of other great posts.
I could go on, but the moral is to seek out successful people that are willing to share their story.