My daughter has taken youtube by storm the last 6 weeks and is rapidly gaining on 2k subs. she mostly does live streams but is also working on making 20 min videos for viewership building. In just 4 days she went from 700 subscribers to 1400, for the moment she is only on Youtube as she gets settled into the flow of this but she soon wants to start on Twitch and Facebook.
One idea is a personal promotional code she can hand out to her viewers, or even some pre-made stickers with her logo.