+1 on SEO and trends. Don't just follow trends though. Be one of the first, if not THE first, person to address an upcoming trend. This means being on top of any potential blowups. Use this to your advantage to build a larger audience. After that, you can focus on more regular content that you specifically want to create.
Other promotion tips:
Take advantage of any reach you have from other social media platforms. If anything, you should also try to build brand awareness and growth in all platforms to maximize reach.
Reach out on other platforms, such as reddit, tumblr, or anything that you think is relevant to your content.
Make comments on more popular channels but don't ask people to follow/sub to your channel. Leave comments relevant to the video you're watching. Your goal here is to again create awareness. The more you have your name out there, the greater the chance people will find your content.
More importantly, create ENGAGING content. If you want more views, you have to have people actually watch yours videos at length. Work on your thumbnails and make enticing titles. Make sure the content actually relates to the title and thumbnail. The first few seconds of your video is also important. Ensure that the first few things people see in your video is something that will want to keep them watching more. DO NOT use obnoxious intros.