Because I haven't unlocked the community tab yet, I'm concentrating on simply engaging with people who comment on my videos. Thanking them, asking further questions, etc. If I know one of my subscribers is a fellow creator, I'll see if they have videos I'm interested in so I can offer genuine feedback on their content as an additional interaction.
I have seen people mention their Instagram as a way to interact or message the creator directly, and I don't know if that's just a natural thing because they had an Instagram audience first, but it's possible you could go that route - create Instagram content to build and communicate with your audience until you get that community tab.
Don't forget to make sure to note any questions in your comments, what people say they really like, what people have their own experiences to share on, because you can "respond" to your audience by making more of those items.
Another idea - how about a little one-sided conversation with your audience at the end of your videos? "Hey, I hope you liked this. I'm so grateful you've decided to watch this far. Here's a question I'd like you to answer in the comments!" I know not everyone watches all the way to the end, but the people who do (like me) may appreciate when there's a little bit extra interaction at the end asking for opinions, or giving us a purpose to our comments.
Good luck!
