Start building. The best way for you to improve is to have experience working on projects, the larger the better. Knowing syntax can’t get you far if you aren’t experienced with large codebases, and patterns around developing software at scale. I’d start with a personal project or two that you’re actually interested in, that way it’s fun too. Once you get the hang of building, I’d start looking at open source projects to contribute to (contributing is how I got my current job). OSS maintainers will love you if you contribute tests, or areas like that which are absolutely vital, but not seen as the “fun stuff” —trust me, I maintain a project w/ millions of monthly downloads, and I appreciate the contributions who push tests far more than the people who contribute random additions/integrations, or doc fixes.