Just post and be active in your niche. And not active with "nice vid" comments. No, if you watch a video you have to genuinely like it and leave a comment that relates to the video and does not direct people to your YouTube page by stating "check out my stuff". Leading comments are fine, like I mention on some car reviews that I reviewed the same car / similar car and I agree or disagree with their findings. It lets people know I have an automotive channel, but it doesn't out right state "check out my channel". If you fake interest however people smell that a mile away. I do not follow anyone I do not agree with, and those I do agree with know me as a brutally honest person. I think most regulars know that of me down here as well. I call people out all the time.