Situation 01You are a week out and want to prepare
The useful work happens before anything is unplugged.
Write down what you have and where it lives. Not for sentiment — for the hour on the other end when three identical white devices come out of a box and nobody remembers which was the bedroom one. A photograph of each room before you pack is faster than a list.
Find your account details now. Not the device details, the account ones. Every speaker, plug and camera is registered to an account somewhere, and reconnecting them at the new address means signing in. An account you set up four years ago with a work email you no longer have is a problem better discovered now than on moving day.
Ask the new provider one question. Whether you can choose the network name and password on the new router. If you can set them to match your old ones, nothing in the house needs touching at all — every device simply finds the network it already knows. It is the single highest-leverage question in this whole page, and almost nobody asks it.
Keep the small things together. Power adapters, mounting brackets, the little screws. These are specified per device and a generic replacement often is not adequate.