There is never a sure fire way to gain subscribers as it is very much up to the person clicking that button on why they do it. All you can really do to increase you chances, is to release high quality content, engage with the wider community and just try to get yourself known by promting yourself over social media if you haven't / aren't doing that already.
Exactly what Zeke Morgan says, it won't happen instantly but will over time
I very helpful way i found was commenting on others videos, really engaging with others in the same position as you
Just make quality content and keep making them! don't stop and stay active in communities and search for opportunities to advertise your channel/video('s) But don't spam them ! And stay motivated !
Following on what zeoislive said, you can post a video for people to look at in "Content", please remember there is rules in each section, so check the sticky posts.