if you're moving instances:

 In Settings > Preferences, you can export who you follow, and then re-import that into your new account

 the "Follows" count on your new account may be a bit lower than your old one - that's because you'll have to re-request locked accounts

 all those you used to follow will get a notification when you follow them!

 Under "Settings > Edit profile > Move" you can make it clear you've moved

@seta Thanks, very useful. Will keep in mind for when I eventually self-host.