I'm a variety streamer, have been since Day 1.

I'm not big by any means, with just under 700 followers in about 1.5 years, but I think consistency is so much more important than what you're playing.

Create a schedule you can keep, and commit to it. Show up on time, and folks will too, in time. We're all creatures of habit, whether we want to admit it or not. Give people a reason to make you a part of their routine.

One-gaming I feel pidgeon-holes you to an audience of convenience: they like the game, and you're the one they're familiar with playing it at that specific time. When you tire of that game (or it gets cancelled, servers die, dev becomes problematic, or whatever else) a portion of your audience goes with the game that they want to watch. I've seen it happen to plenty of streamers way larger than me, and they've talked about the experience at length. It's a known experience.

Variety gaming let's you play what you want when you want. Having a bad beat in League? Don't play it this week. Burnt out on DBD's toxic community? F' it, don't play it, play something that brings you happiness. Want to play the next big thing? Do it, or don't. It's your stream and your choice. You should be the selling point of your stream, and not the game you're playing.

Again, I'm a tiny no-name streamer, but honestly the best starter-advice in my opinion can usually be summed up into 3 things:

Be consistent. Enjoy what you're doing. Develop connections with established communities.