Boris may i ask you how to properly use cards and endscreens? I mean how do you keep you viewers to watch more?I use Youtube seo...In my humble opinion, if you can't create a viral video, SEO is your best option to hit the ground runing.
I use Socail sites like Twitter, Reddit and forums...Facebook is no good for me.
I use playlist, card, and endscreens (interconnect my viewers to keep watching my content) to increase watchtime which also leads to higher rankings...Hope that helps