For example, you can read any book on throwing the javalin and the quality of the book really doesn't matter much: it could be an amazing book, but no book is going to enable you to throw the javalin well. It can tell you how to do it, give you tips on what to try and what to avoid, but it can't help you in the actual doing.
You probably know enough about the practices to be able to design and build something already. The key is action; to do it, and to learn in reality what works and what doesn't. It's like throwing the javalin: the first few are going to be awful, but if you know the principle, after a bit of practice it will start to become a respectable throw (even if not world-beating).
I use the javalin metaphor because people can spend a lot of time building a SaaS. Treat each attempt as a throw, and recognise that if you spend the next three/six months on one throw then you're really not going to learn very much and it's not great practice.