You need to do a bit of research to find a courier that covers the item you plan to sell and make sure you pay sufficient postage to cover the value. Check any exclusions - many couriers don't cover, for example, glass items or antiques.
When you post the item, make sure you add the tracking.
Really, for larger parcels, the system has not been changed by Simple Delivery.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)