What arrangements should be made by the seller before settlement?

As the seller you should deal with the following before the settlement date, where they apply:

arrange for the real estate agent to give the keys to the buyer on the date of possession or, if the property is your principal place of residence, at noon on the day following settlement;
keep your insurance in place until settlement has actually happened, to ensure you are not uninsured on a property you still own;
cancel the electricity and gas services, remembering that anything you consumed up to the date of possession or settlement is yours and is not apportioned at settlement;
cancel or transfer your telephone, internet and other telecommunications services; and
make sure the property has at least two RCDs and mains powered smoke alarms, which is a legal obligation on you as the seller.