By plane:
Olbia - Costa Smeralda Airport
Many national and international airlines offer flights to this airport

Ferries:
You can reach Olbia by car. Ferries from Italy: Genoa, Livorno, Civitavecchia, from Savona via Corsica from France: Nice and Toulon

Car hire:
There are several car rental companies operating at the airport and you can easily book a car in advance or directly on arrival.

How to get to Porto Rafael:
From Olbia-Costa Smeralda airport, or from the port, follow the signs to exit the city in the direction of Arzachena and then follow the signs to Palau. Just before Palau, follow the signs for Porto Rafael. The drive should take about forty minutes, depending on traffic conditions.