What does not come with you
Be honest about this part, because optimism here is expensive.
- Followers. There is no export and no forwarding. A fraction will follow you, and the fraction is smaller than you expect.
- Direct message history, which is often where your working relationships live.
- Content hosted on the platform, in the platform's format, with the platform's comments attached.
- Any link that pointed at your profile there, including ones in other people's articles.
What does come with you
A shorter list, and it is entirely made of things you set up yourself.
An address you control, which keeps working regardless of what happens to any platform. A mailing list, which is a direct line. Files you host, which do not disappear when an account does. And the statistics you kept, which are your own record of what worked.
Everything on that list can be arranged in an afternoon, years before you need it.
Point at yourself, then at the platform
The single most useful habit is to stop sharing platform links directly.
Instead of putting a platform URL in your bio, in a poster or in an article, put your own short address and point it at the platform. Then, when you move, you change the destination and every reference follows.
It feels like an unnecessary step until the first time you need it, at which point it is the difference between updating one record and hunting through five years of other people's pages.
The week before you leave
- Announce the move on the platform you are leaving, more than once, over several weeks.
- Put the new destination behind an address you own, so it can change again later.
- Export whatever the platform lets you export, including your own posts and any contact list.
- Update your bio page first, because that is where people will look when they cannot find you.
- Leave the old profile in place with a pointer, rather than deleting it. A dormant profile that says where you went is worth more than a 404.
The page is the constant
Your bio page is the one thing that does not need rebuilding, provided it lives on an address you control.
During a move it does the heaviest work: it is where the people who lost you go looking, and it is the address in every article, poster and old post that still points somewhere.
That is the argument for setting it up before you need it, rather than in the week when everything else is also happening.
Afterwards, look at the numbers
A month after moving, the statistics will tell you something uncomfortable and useful: how much of your traffic actually came from the platform you left.
Sometimes it is most of it, which is a hard month. Often it is less than expected, because a lot of traffic was arriving from search, from other people's links and from the mailing list all along.
Either answer changes what you do next, which is the only reason the numbers are worth keeping.