I haven't had time to write a real thing but I'm seeing a ton of new people, so here is my quick/dirty advice for people just arriving:
1. Just use the website at first. Third-party apps are great, but they often lack important features and may act weird when server loads are high, which they are during big migrations from Twitter. I started understanding a lot more when I switched to the web version.
2. Picking the right instance matters, but not for the reasons listed in most Mastodon documentation! Topics matter much less than filters you want applied over the gaping maw of the unmoderated internet.
Assuming you do not want to live your new life on the federated equivalent of 4chan, pick an instance with clear, strong mod rules and a nice big blocklist to keep the nazis and trollfarms away. (You can find this stuff on the About page for most servers.)
@arranrp It is! But you can't take your posts with you—you open a new account and then migrate your follows and followers following a slightly arcane but googleable process I won't attempt to summarize.
It's clunky, but not difficult.
Erin Kissane
Arran