Most likely, no one will read your messages if you're casting them to a channel that hasn't approved you, or writing to someone who isn't following you.
So, you should focus on two things:
I've gathered 300 of my active and interesting followers that I'll be interacting with. I've organized them by priority, divided into 10 groups, and sent them to myself in direct messages.
The rules of the game have changed, so make sure to adapt.