For gaming, I think at some point, you have to try reddit. It's hard to get noticed by doing nothing in the gaming world. We managed to get 100 views on one video after posting there. But it won't work for every game. Has to be popular to start with. But they can be super picky and dislike your video. It's a gamble on there.
Post to social media, I think twitter works a little.
Use good, relevant tags.
Post regularly and don't let your channel die (don't stop posting for a month)
We can manage to get a bit of views. It's the quality of content I guess and getting people to sub that has been the problem for me.