I have done this in the past, my suggestion is PLAN everything. Make a document that lists what each VLAN will be used for and the IP subnets for those VLANS.
For subnets that will have devices with Static IP I would create a document for each network and list the new IP address that devices will be moved onto. The great thins with the Meraki dashboard is use you can export the client list from the Network-Wide > Monitor > Clients page to ensure you don't forget anything.
Then I would move one lot of devices at a time i.e. servers, printers, client devices etc. I would personally move your servers first and make sure they can access the internet and then move client devices.
If you have Meraki switches you can add ID tags to ports which will help you identify device type and then change an entire lot over to its new VLAN quickly.
How many devices are you working with?
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