I want to stream on twitch but I still want to have a conversation on skype but I don't want to hear my voice or the people/person Im talking to on skype. here is a good video:
FFsplit is a good option too. It's not quite as stable as OBS, but it's more resource-efficient and has a few features that OBS doesn't have (such as separate webcam/mic-audio/output-audio sync adjustment). And they completely overhauled the GUI recently so that it's much easier to use.