A lot of developers are helping the community by making their source code public or publishing packages to npm or something like that. Are there other ways to help? Like helping to find a bug, discussing about how to setup an application for a certain use case or anything like that? Answering questions on Stack overflow is an example but is that the best way?
The “best way” depends on the project and its need, or immediate most pressing needs. You may refer to their contrib docs or ask.
But generally, any quantity and quality contribution helps. Community support and issue reproducibility and testing being low-barrier entry ones. Next lowest barriers being translation and documentation.