Olbia is a ferry port, so you can easily get in by ferry/cruise ship.
Beware the way locals drive: racing along the narrow and bendy roads in the hills.
Olbia Travel Information  The most comprehensive online guide to Cagliari with online booking, itineraries, tourist services, weather forecaset and photo gallery!
You may encounter poor road conditions, with potholes and open grids. Also the skill of some drivers leaves something to be desired.