There are also websites listing such projects, search for "oss help wanted" or similar. E.g. http://github-help-wanted.com http://github-help-wanted.com It is

There are also websites listing such projects, search for "oss help wanted" or similar. E.g. http://github-help-wanted.com http://github-help-wanted.com It is however much easier if you contribute to a project that you already know and use personally.