I learnt 100x more about running a startup after starting one, and initially doing a bad job, than by reading thousands of blog posts.
I’ve found in that sort of situation, it is tremendously useful to find a good book or other form of guidance so that I have a mental framework to organize information and a way to imagine myself succeeding. You know the OODA loop? I think theoretical knowledge really helps with the ‘Orient’ step.
But otherwise, these are lessons. If you don't focus, and so get nothing done, you'll learn to focus, by saying no to some things, even if everyone tells you they're critical.
Conversely, if you focus too much on one thing, do it excellently, and fail at other things, which I've done, I've learnt to do things to the extent needed, not more, as opposed to building a car with the world's best engine but no steering wheel.
This has just been my experience. I respect that it may not work for you.