What we have found succesful for youtubers starting out is a focus on Facebook, Twitter - and if you're gaming Player.me . However, you have to do more then just share your videos .. You do need to be active tweeting about different things (including Trends). Every time you share your video across several mediums - it increases your rankings.
Remember, Being a succesful Youtuber is a marathon - not a sprint.
We have Twitter and instagram, still coming to terms with how to engage properly with a community we fit in to. You could say we were quite native to the idea of social media thinking we could just jump right in at the deep and have loads of people wanting to talk to us and watch our stuff.
"Remember, Being a succesful Youtuber is a marathon - not a sprint." this is defiantly something we will take comfort in when we post our videos and they only get a few views. They all seem to plato out at around 20/25 views for some reason but they may be a slow grower.
Did you find a lot of your subs found you on facebook & twitter?