What do you want to do?
Everybody's different. There's no real predetermined path for music. There's knowledge that has been accumulated over the years (varying amounts of centuries, depending how long your instrument has been around). There are combinations of sounds that just seem to make sense (David Byrne's "How Music Works" devotes an entire chapter to ratios found in paintings, architecture and planetary orbits that mathematically match up with the kinds of sounds humans like), and technical things that, if you learn them, will make you a more efficient/effective player. You don't need to learn any of it if your music doesn't require it. Kurt Cobain proved that point in the early 90s. But he had a clear goal: to become the biggest rock star in the world while staying true to his punk rock roots. And he nailed the technical aspects of his music. Morrissey and Johnny Marr have both attributed The Smiths' unique sound to the clarity of their vision - Morrissey the tragicomic poet; Marr the rock guitarist who had to avoid "rockisms." While Four Tet uses a bunch of gear, he doesn't get too complicated with each piece - just makes it work and exploits what's weird about it. You can learn all the rules of a particular style, but music that simply recites the rules is never the legendary stuff, because it doesn't move us on a gut level.
When you have a destination in mind, you can pick out which skills are relevant to you, and learn them. When you don't have one, you spend a lot of energy on "Just In Case." You might buy a shelf full of books, videos, some really nice equipment. Will that stuff mean you're ready? Do you need permission to go and play? I believe this view is actually counterproductive. Yes, you'll take in more material, but all the while you're worried about not being good enough, not knowing enough, doing it wrong. As we know, anything you do repetitively is a form of practice. And "practice makes perfect." Would you choose to spend time perfecting the art of feeling unaware and unprepared? Is that why you picked up an instrument?
There is another way. A musical practice can be like a doctor or lawyer's practice (credit due: I got this idea from Jerry Granelli). It can be something you do, rather than something you polish up and display. Are you trying to communicate? Make a billion dollars? Join a band? Blow people away with your technical prowess? (and if so, WHY?) Push yourself to achieve more, because it feels good? Feel like you can "just play anything"?
It all starts in the mind. If you can be crystal clear about what you want to achieve, doing it is the easy part.