Create a facebook page for your channel and invite all your facebook friends to the page. Post your youtube videos and promote your youtube channel on the page. If you have twitter, regularly post the link of your youtube video there with relevant hashtags, along with other ways to promote your channel. Create an instagram page... You can't post youtube videos there, but you can still promote your channel and your brand by posting photos regularly, and somehow leading people to your youtube channel.... Hope this helps. Your subs will truly increase!