How do you self-teach yourself more complex software dev skills>

Keep practicing.

Read other people's code, for example open source project. Contributing to open source can be good practice also.

Find a mentor.

Pick a team at work that has the skills and culture+capacity to mentor you.

Don't teach yourself complex software dev skills. Teach yourself complex software problems and learn how others have solved them in the past.

BUILD SOMETHING.

Learning concepts without the ability to apply them are essentially useless.

Get your hands dirty and build something that would be valuable to you and solve a problem for yourself.

Don't get hung up on doing it "right". Focus on making it work. Don't worry about how it'll work for a million users. Right now your focus is on making it work for one user.

As you go you'll hit walls. Research how to get past them and keep going. Again, you're going to make mistakes. DO NOT GET HUNG UP ON THIS.

Making mistakes is part of the journey. Even the best software engineers in the world rarely get things right their first try. It's part of the process.

First focus on working on projects instead of improving your skills. The concepts you learn are usually a solution to some problem. Things are easier if you first encounter the problem yourself and then learn the solution, than if you do it in reverse. It is ok to do things poorly when you are starting out.

Like others have said, practice is key, however I'd like to add that you should not feel too discouraged if it feels like you're making no progress. You're probably making more headroom than you realize. At least personally in programming more than anything else I have occasionally only seen results after I came back to a concept I gave up on learning.

Do be aware of getting stuck in local minimum though. I know it probably feels like bad advice but I figured I'd give it since it helped me personally, so maybe it might help someone else.

When you're at that point, it's usually a sign that you need to start applying what you learned. There are two parts of programming:

1. The concepts, the theory which is honestly the fun part.
2. Dealing with the little annoyances, setting up a development environment, learning APIs, wiring things together, running into problems there is no clean solution for and implementing something that works.

The second part feels unimportant, something you can always learn later, but it takes time to learn and get good at, and what you need to learn to start to effectively apply more advanced concepts. Otherwise you're learning things you won't be able to use.

You need to practice what you have learnt. Even if it is a hobby project, make it as clean and elegant as possible to learn the implementation of the techniques. Practice makes perfect. And take notes. Organized, detailed notes. Use something like trilium, nextcloud or Google docs.

Practice practice practice, always challenge and improve on your foundational skills. Everything else gets easier. Write code and solve problems, struggle through it in whatever way works for you. There's not really a shortcut to getting more experience than to put in the work.

It's especially important to try and do things the "right way" as a learning/growth tool. It will take longer, and you'll rewrite your code multiple times, but the next time you encounter a similar problem you suddenly know exactly what to do and the constraints around the problem.

Do this often enough and you'll find yourself having a general idea of how to solve just about any problem you come across, and how to do it elegantly.

No matter what you learn, keep the foundation strong. Religiously follow the "First Principle". For example, instead of learning tons and tons of web framework, try to learn the fundamentals of the language first and how networking works.

Try to understand the concept by yourself. Verify the inert knowledge. Don't rush for the quantity. Take your time and build a strong root. Make time your friend.

One thing i undervalued for most of my career was just reading code.

Get into the habit of digging into open source repos that catch your curiousity, and try to grok the way the project is layed out, what namespaces/files exist, what some of the core functions are, where the complexity is housed.

It’s all about getting exposure to patterns, especially if there aren’t other people to work with in your day to day.

Lots of good advice already in this thread, but I'll add: Try interesting professional practices in your personal projects. Try to build your code test driven development, write a contributing guide, keep a changelog, set up automated testing, set up static code analysis, generate a coverage report.

These habits certainly aren't needed for your hobby coding, but they can teach you things about how your coding style compares to others (and be sure to add any you've done to your resume, of course!)

By not learning. Software should be simple not complex.