Antaryami. 2.1 facts

You need to keep reminding people to subscribe and your video descriptions are a great place for it.
For example if you are doing a play-through for a quest and it goes for 30 minutes. You could write in the description something like this to help viewers:

0:00 Where to start quest

5:00 How to find item

10:00 How to give item

25:00 How to fight boss