Are there any open source projects you use in any of the work you do? That's a good place to start. Occasionally, I'll look at dependencies in projects I'm working on and see if they have any issues I could help with. It's a good way to give back.
Also, contributions don't need to be large or complex. I've made contributions where the only thing I helped with is to fix some spelling mistakes or fix typos in documentation.
Some general advice when you want to make a contribution:
Good luck! Contributing to open source is a worthwhile endeavor. If you make it something you do regularly, you'll have a handful of contributions one day.
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