Use tags!

You should tag your videos appropriately. That's how people find your stuff on Youtube as well. Add relevant tags.

I've read from somewhere that you're not suppose to put tags in the video descriptions. I guess that's why Youtube have dedicated text boxes for tags.

Share your videos on other social media sites

If you have other social media sites, you can also share the video at those sites so that your video reaches more people. You can also use the same brand name, profile picture on other social media sites to create a consistent identity. And add links or embed your video to your social media sites so that people can check out your other sites.

Collaborate with other influencer

This will get you new views and subscribers. You can collaborate with other influencers and use cross-promotion to grown both channels! Look for related channels to collaborate with though.

Post Great Thumbnails

They may seem like a small thing (because they are), but thumbnails can have a big impact. YouTube advertises other videos via thumbnail in its sidebar, so you want yours to stand out among the pack. The same goes for YouTube search. Videos with a catchy title and appealing thumbnail usually rank higher, even if the content itself isn’t as valuable, because they have a higher click-through-rate (CTR). To get your CTR where it needs to be, try using tactics such as highlighted areas, arrows, large text, and unexpected or unusual images.

Leverage YouTube Cards

YouTube rewards channels that keep viewers on their pages longer. These longer average watch times mean people are truly engaged with your content. (You can see how long people are staying on your videos by using YouTube analytics). By adding YouTube cards, you can add additional recommended videos at the exact point where users are currently dropping off. Though they may abandon that video, users will be taken to your other content and stay on your channel, increasing your channel’s ranking.

Increase Your Uploading Frequency

This tip may sound intimidating at first, but to grow your audience, you need to increase your posting frequency to at least one video a week. Consistency is of the utmost importance. Try to post at the same time each day or week (depending on your frequency), and keep your subscribers updated about when new videos will arrive. Then stick to your schedule.