A good mix between SEO and legitimately good/unique content is your only way into the big leagues of YouTube.
Master the art of SEO and content production, and you'll get those views that you desire. But I need to stress, there is no way to get more subscribers on YouTube. Referring to them like that makes it seem like there isn't a person behind the computer that clicked the button.
You must make generally genuinely enjoyable content in order to get this REAL PERSON to click that subscribe button. Nothing else on or off YouTube can get that done with a high return rate.