Before you let go
The exit plan.
If you're thinking about a change with your IT person or provider, collect and verify these first, while cooperation is still possible. They are numbered because the order matters.
Non-negotiables
Secure these before anything else.
Next
Then these, in the same week if you can.
This is a starting point. Every company is different. If you want someone to walk through it with you before you make a move, it stays confidential.