Subscriptions are fine, but it can be hard to get new users without a free tier or free period where they can try it out and see what the value to them would be

Subscriptions are fine, but it can be hard to get new users without a free tier or free period where they can try it out and see what the value to them would be. And then you don't want the free part to be too good so that people never upgrade, or you have to police people who make a new email address every month to get another free trial. Advertising is like poison in the wider fediverse right now... which IMO means there is a big opportunity for an advertising-based server. Just be prepared for some of the larger peers to block you, so you have to make sure there is enough value on your local instance to draw a crowd.