The Airport is mainly served by Ryanair and other low-cost-carriers.
There are a few bus lines going to most cities within a 200 km radius. They are not cheap though.
Basically, you can hitch right in front of the airport building. However, you will miss the cars coming from the long-term car parks. A better way is probably to walk about 1 km in direction of the exit (over a bridge), where the roads from all car parks merge. The traffic is not dense and mainly local. An alternative is asking the people leaving the Arrivals Terminal. Good chance to get lifts this way.