Before starting out I have some things to say.
Firstly,
I have tried these ways and it works out in the LONG RUN because
everyone puts different amounts of time and resources in making a video
so I cannot tell an exact time period.
Secondly, I am also a small YouTuber who has tried to grow.
In
the month of September 2018, my channel has 700,000 views but in the
month of December 2018, my channel has over 1.4 million views (double
the amount!).
With all that in mind lets continue to the main segment,
How to Grow a YouTube Channel in 2019
Number 1: Build Videos Around a Single Topic/Niche
Build your video around a single topic/niche is the best way to get the traffic you want and grow your audience. Many people who are unaware of SEO best practices skip this step, but it’s crucial if you want your videos to get the maximum amount of viewers. Try using a keyword tool to look for the most searched keywords in the niche you’re looking to target.My niche is how-to & tutorial.
Number 2: Use Social Media to Get Traffic in the First 24 Hours of Publishing a Video
You can't rely on YouTube to do all the work and promote your video for you. It's important to use social media to your advantage and build a following on other platforms around your channel niche and interest.Get those views and watch time up in the first 24 hours!
If you can create a traffic spike the first day a video is published, it will perform better on YouTube. What channels are you on? Facebook, Linkedin, Instagram, Pinterest? There are many from which to choose.
As Facebook is not for me, I've just made a new account on Pinterest!
Number 3: Make Click Worthy Thumbnails
It may seem like a small thing, but thumbnails have a big impact. In YouTube, you want yours to stand out among the pack. The same goes for YouTube search. Videos with a catchy title and an 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.Here's an example from my channel:
Number 4: Make a Video go Viral
Try to make a
video go viral as it can help your channel in getting a huge boost in
views and subscribers too! So I had made this video on how to fix a not
working laptop keyboard, in the first two months it had got only 200
views but after some time the snowball effect started and my video blew
up currently it is sitting over 950,000 views (almost a million!) 
Number 5: Engage with Your Audience
It's important to interact with your audience. If you’re just posting videos without encouraging comments and discussion, you’re missing a trick. YouTube rewards channels with great engagement, including the overall time spent on the channel, watch time, likes and dislikes, and most importantly, comments. Try to respond to every comment you receive (if possible!) and ask users to engage with audio/visual prompts. Like comments and reply back to them.Number 6: Ask Your Viewers Questions and Ask them to Subscribe
When you ask your audience questions, even when it's a small audience they are more likely to engage. It's a fact that someone who comments (positively) on a YouTube video, is more likely to eventually become a subscriber.In YouTube Analytics, I've seen a direct link between growth in comments correlating with growth in subscribers.
FINALLY BE PATIENT AND ENJOY THE JOURNEY!!!
You are welcome to share your ideas with us in the comment!