If you want to take a deep dive into Python and skip all the beginner tutorials that assume you don't know anything about programming, then this is the book for you!
Does the advice you give depend on the size of the development team? If so, how does your advice change? and where is the limit for small versus large teams?
If you haven't tried approval testing yet, you definitely should. It makes unit testing a lot easier, particularly for legacy code or for verifying complicated objects.
If you are having trouble marketing your products and services, perhaps instead of focusing on what you sell, you may get better results by focusing on building a community of people with shared values.