Posting videos on Youtube is so easy that pretty much everyone has at least one video uploaded, and many people constantly upload content in the hopes of becoming known and building a following. In fact, some people are so large that they are partners, which means that they can actually make money from their videos through Adsense ads.
Generating a following and getting a ton of views for your videos is pretty hard to do though. It is very hard to become an overnight success on Youtube, and most Youtube partners either get lucky or work for a very long time on generating enough views to become well known.
The best ways to get views on Youtube are to contribute to the community, promote your videos online, and set yourself apart from the pack.
Contributing to the community doesn't mean that you should comment on only large videos that get a lot of views. In fact, it is much better to comment on videos without a lot of views and comments because then your comments will have a much larger effect, and people will see it more often. Make sure that your comments are creative, and constructive. Posting insults or trolling on someone's videos will not earn you subscribers or comments in return.
Promoting your videos does not mean spamming the link to everyone you know. Instead, using a site like Reddit, that allows users to target the audience that they want to promote their link to audiences that would actually be interested in the content of the video.
Lastly, creating videos that are different and stand apart from similar videos on the same topic are a surefire way to get noticed, because your content is 100% unique and nothing similar can be found. For example, if you're vlogging, you need to take an angle on your life that someone has not taken before. For example, Kevjumba made a lot of videos with his father and other family members that was completely new and had not been done before.
Following these three techniques is a great way, albeit a hard and drawn out process, to getting a large following and a solid base of subscribers. Keep in mind that becoming popular on Youtube is not easy, but with unique content and persistence, anyone can become successful making online video content.