^ ThisI see this question a lot and the answer is quite simple. Make videos people will share with their friends.
I personally don't rely on social networking. For people to share, you need a following already. Of course if you get one on YouTube, people will then follow you on social networking. I have always seen these things as something to get up once you've got the following (you can tweet all you want but with 4 followers who sub you on YT anyway, it's unlikely you'll get much by way of promo).^ This
And to your Twitter and Facebook stuff, make sure you are trying to expand them. Yes your dedicated fans will follow you but make sure your tweets and posts are entertaining. Make sure you use hashtags, worldwide trends correctly.
Here is how I think of it. I am a wrestling fan. When I was younger, I was a fan of guys like Stone Cold and The Rock. I always wondered what they were up to. Now they have Twitter's and they tell their fans what's up, not only talking about wrestling. The Rock will post pictures, show where he is, talk to his fans, make some commentary, etc. So think of it that way. Think your followers are there to see what's up with you. Also sometimes if you make a funny tweet or facebook post that has nothing to do with your YouTube comment, your fans retweet it or share it out, which goes out to more people. Then if you use the Worldwide Trends as extra commentary you will be in the list of people who posted tweets and a worldwide amount of people will see you. You get what I mean? It is not just about promoting your work on YouTube, it's about you promoting you as a whole. Don't think you only need "YouTube subscribers." Get every type of fan you can.I personally don't rely on social networking. For people to share, you need a following already. Of course if you get one on YouTube, people will then follow you on social networking. I have always seen these things as something to get up once you've got the following (you can tweet all you want but with 4 followers who sub you on YT anyway, it's unlikely you'll get much by way of promo).
That's just me though, maybe it works for others
We do the same thing.. Our Mom's love our show.I try and make good content first, then I ask for friends, family, and twitter followers to look at my stuff. They watch my stuff and at the end I ask for their likes, subs, and shares. But I have to say this, I have a couple of YouTube big guys in my niche and when they swing by and leave a comment my subs go up for 2 or 3 days and that's awesome of them. Why do they do it? Because I like their stuff and commented on their videos. Plus, they are nice people. I did not ask them to "please check out my video" either. I wasn't trying to get noticed, I commented because they're stuff was awesome and I respected what they were doing. So you might want to make sure you add to conversations of people doing cool stuff like. Now, don't be all super fanboy or stalky with it.
Summary
I ask friends, family, pinterest and twitter followers to look at my stuff
If they stick around to the end of the video I ask them to sub, like, and subscribe
I comment on "big guys" YouTube channels if I'm diggin their stuff, but I never ask them to do anything, if I become a real member of their community they MIGHT check me out
If someone big watches your videos/comments your subs will go up for several days