Every topic has its keywords - determine what is popular in your field now, what information people need now. There are even tools for this. Next, use hashtags, add end screens to each video, create playlists - basically use all the tools to the maximum. And finally - engage your audience through comments or social networks, it is not important. These tips may not be unique, but they work in one way or another. Innovative ideas usually work in the beginning, but not long term.