Follow these steps:
- Go and find an open-source project on GitHub that you find appealing and that makes you motivated
- Learn how to contribute to it (read its contribution guide, project setup guide, etc.; dissect its code quality settings); this is important; you want to be a good and respectful citizen and not waste anyone's time with super subpar contribution attempts. An added benefit for doing things that way is that when someone is genuine and honest with their work and contributions, people can feel it and will be more likely to provide you support beyond regular, e.g. more thorough peer review feedback that you will learn from a lot.
- Find a small task you can do in the project. Usually, the readme suggests where to start.
- Once you start with the open source contributions, just keep contributing to open source permanently.
- Look for a job. You don't have to wait to start looking for the first job.
You can do it