Travel insurance to cover theft, loss and medical problems is highly recommended. It may also cover you for cancellation, delays to your travel arrangements or an emergency flight home.
Check your policy covers any activities you might be planning such as diving, motorcycling, climbing, even...
Sardinia is a safe island, but use common sense.
Stash away your valuables and lock hire cars.
In case of theft or loss, report the incident at the questura (municipal police station) within 24 hours and ask for a statement, otherwise your travel-insurance company won’t pay up.