Ask HN: Best ways to volunteer?

What are some of the best ways to volunteer as someone working in tech? Many of us have valuable skills that we can put to use such as software engineering, data analysis, product management, project management, etc. What are some of the best ways to use those skills to help out those in need? Ideas that come to mind: * Contributing to civic tech projects * Contributing to open source projects * Helping out non-profits * Donating money made by using the aforementioned skills Which methods of volunteering or giving back do you think are most effective?