Highfalutin' Low Carb
Loving YTtalk
ENGAGE in the community that is your niche. Make thoughtful, genuine, ON-TOPIC comments on other channels in your niche. Ask questions, get involved. It's done more for my channel than almost anything. I've gotten a few "shout outs" from large channels in my niche this way. Particularly if you can catch one of the big channels in your niche Live Streaming. Get in there and chat with them! I started my channel two months ago and am about to cross 800 subscribers, mostly from just being involved in the community surrounding my niche.