Many coders start out self-taught like you. I did, and then studied for an IT degree and got professional work.
Here's a few things that I wasn't exposed to until I studied /turned professional - maybe some of these are the practices you are talking about?
- Version Control (Git, CVS, Subversion, etc.)
- Database design
- Performance optimization
- Caching
- Design Patterns
- Object oriented design
- Unit testing
Maybe you know these things already, but not knowing these things isn't going to stop you, none of those are worth losing sleep over, you'll pick up what you need on the way.
However, if I had to pick one thing out of that list that I wish I'd encountered sooner it would be version control.