I believe I've said this on many other posts, but it doesn't really seem to get old. Basically, network, network, network. If you work with other YouTubers to help each other out by sharing their videos around, and you ask them to do the same in return, it's a win-win. It offers a legitimate way to get views and such, and it gets your content out there. Collaborations are also a good way to get the word around about your channel. Being known in places like forums is a good idea too, because people know who you are and might get curious. Don't give into the temptation of sub4sub or bots like that, if you've been considering, they offer absolutely nothing.
Edit: Also, good tagging, titling, and describing would help. Annotations might help too, since they remind people to do certain stuff, since a lot of the time they forget.