Gotta make the transitional learning curve almost 0.
Namely give people a solid app to use (I use Thunder, which is a near clone to the reddit apk called relay for reddit) and implement a way to set up a screen name easier than having to "mysteriously track down some strange thing called an instance" and create your name there and then going and finding the apk to use and logging in under your instance and screen name and password.
It's a turn off to how easy literally everything else on the internet is to set up. We need an apk that has a "new to lemmy" walk-through that explains how to navigate and sets you up with a login and instance. An apk with a 5 minute set up tutorial to get you started up and using lemmy would go a long ways in people coming and staying.