The /r/piano FAQ (https://www.reddit.com/r/piano/wiki/faq) is a great starting point. There's a ton of resources available online, so the trouble is actually in picking the really good ones. Still, if you want to play well, you should probably get a teacher.

As for myself: I've started lessons about 6 months of trying on my own. The teacher's role is to point out the small things one does not even notice when learning on one's own -- and those can really make a huge difference. But in the end it is all about the learning process -- seeing what works for you at any given stage, filling the gaps, re-evaluating periodically if your approach should change. And it's a long-time project. Most people become comfortable after 10 years or so of daily practice. So either you're extremely committed/desperate/forced/enjoy the learning process with the long-term goal in mind, or you quit.

The specific resources I can recommend are:

  - Lypur's video courses on youtube (both piano + music theory)
  - "Piano Handbook" by Carl Humphries
  - "All About Music Theory" by Mark Harrison
  - http://www.musictheory.net
  - Willi Schneider's "Klavierfibel"