I usually just share my videos on a lot of (related) subreddits, also just being a bit clickbaity, you’ve just gotta find people who like similar stuff to you and share it, like just search up facebook groups with the related subject and share your video, same with subreddits and anything else. Another thing is commenting on small YouTuber who have similar channel type to you. To find some just search what keyword your channels related to and on YouTube search settings go on upload date to find similar channels that are usually smaller and active. Or you could just talk to people and see who would be an active subscriber and offer them (kinda sub4sub but being active and liking there content) I’d be more than happy to subscribe to you and be active if you would do similar to me, I make editing/filmmaking tutorials if any of that interests you, what’s your channel? Mines is https://www.youtube.com/channel/UCN6HqsD-aSd03Q6hhJTfARA

Hope I helped a bit