I advise you watch The George Show on the freedom youtube channel (https://www.youtube.com/user/mcnfreedom) George mentioned one of the best ways to grow is by collaboration. Go and find yourself another youtuber with similar amount of subs and similar content and ask for a collaboration. Another way that helps is to advertise your videos on many different platforms eg: Twitter, Skype, Discord, Reddit, Facebook, Instagram and even here on the community forums. Hope this helps.