I don't know about the best way but the easiest way is to start a project yourself. It must be a real world project that can be used by others. Once you are sat

I don't know about the best way but the easiest way is to start a project yourself. It must be a real world project that can be used by others. Once you are satisfied with it, attach an appropriate free license and upload it to your github repository. Then it's important to use it, maintain it and even talk about it. Start simple. I started with yet another node.js template engine, for example. It's also important to respond to any response from the community. Also, not to be pedantic but you probably mean "free software". "Open source" software is not necessarily open to be edited and republished as free software is.