What can you learn from serial entrepreneur, author, podcaster and angel investor Rob Walling? Well, quite a lot! However, this book is from 2011, back when he was down in the trenches being a solo micropreneur developer so if you're not a developer this is probably not for you.
Coding is hard.
Starting a business is hard.
Coding your own business is compoundly harder.
But, silver lining: you're not alone. Others have done it before and others are doing it right now so you might as well take a shortcut and learn from others mistakes instead of making them yourself (shoutout to IndieHackers).
The book is obviously centered around marketing, sales, and getting your startup/project/idea to be profitable. But there's also lots of lessons to be learned about resiliance, hard work and optimism. Topics covered include: marketing, entrepreneurial mindset, running your company, recruiting & retaining and micropreneurship.
What I enjoyed the most is the developer perspective Rob gives to every aspect and how related I felt whilst flowing through the pages.

Remember, ideas are worth nothing on their own. And these days with how easy it is to build an application (this quote is from 2011), your code isn't worth much, either. This hurts me as much as anyone since I'm a developer.
WhatsApp: send and recieve messages. Instagram: share pictures. Gmail: send and recieve emails. Amazon: connect buyers with sellers. Tesla: electric cars. And you can complete the list yourself.. None of the previous are exceptionally great ideas on their own but rather just average ideas turned into (good) products with great marketing (and execution).
Ideas (and in many cases the code itself) are not worth as much as we think. It’s marketing that most often makes the difference between a successful and a failed startup.
So basically: start marketing the day you start coding.
Or, actually... before you even start coding! Validate your idea, build a prototype, show it to people, gather feedback, improve it and keep going.
You can get the book for free on www.robwalling.com.