Promotion (though I wouldn't promote on other people's videos) is good to get people to look at your videos.Promoting, either on others videos, social media, in person, using SEO strategies, etc.
Being part of a community with similar interests will likely result in people who will watch more than one of your videos and stick around longer. People whose channel I genuinely like, I comment on their videos about what I liked (without promoting my own channel). The youtubers who generally appreciate those comments take time to respond. Good for building connections which could help out in the long run.Or being a part of the community like having genuine interest in someones channel and making friends and talking to people on social media
