Everybody is so focused on subscribers, most totally neglect the value of the people beneath the number. Everybody should be seeking fans and not subscribers.
Which is exactly what you are asking. You want people to watch your every video? You need to:
1. Provide content that the viewer can not turn away from. You need to provide value, give them a reason to want more.
3. Be approachable. We all enjoy television. YouTube videos are not going to be as produced or skilled, but they offer the opportunity to discuss and talk with the creator. Be aware of your audience, be genuine, appreciative and responsive to their needs.