I find one of the most helpful ways you can encourage people to leave hellsites like #Twitter and #Facebook to try out #mastodon / the #fediverse / etc isn't to just tell them "join mastodon" and hope they end up picking a good instance. Actually go the extra step of finding an instance that, to you, an experienced user, seems well moderated, and at least somewhat aligns with that person's interests so they'll find other people's content to keep them interested, and suggest that one directly. @eldritch.cafe remains the first Mastodon instance I ever joined, after my friend and I specifically looked for a server that allows nonsexual female nipples without being focused on actual sex work, and all in all it's been a great experience (and has completely ruined me towards any server with less than a 5,000 character limit, haha).
Especially considering how tech-inclined so many (pre-Twitter-migration) fedi users are--keep in mind that most of us (me included) are not so knowledgeable about this stuff straight out the gate 😜 We need a little extra guidance, and if you truly think that the fedi is a better alternative, you need to make the extra effort in improving #accessibility to your chosen platform. (It also helps tremendously in making sure that someone's first interaction with mastodon isn't on a huge server with little to no moderation, opening them way more up to attacks from racists, etc than if they had started on a heavily moderated server that is already #defederated from instances that allow that abhorrent behavior)