Cairns is a town in Queensland, Australia.
Hitchhiking out of Cairns is very simple,
The by far easiest way to get anywhere from Cairns is to just walk to main intersection of Highway 1 and walk until you find a good place where cars can pull over. Which can, incidentally, most of the time be found just 20 meters from the intersection.
Towards Port Douglas, Mossman and, in dry season, Cooktown
Around June, July and August, this is the best way to get to Cooktown. Make sure to double check with people since it is a 4 wheel drive road, albeit a very trafficked one because it is the quickest way to get to and from Cooktown.
However, instead of trusting the folks in Cairns as to whether the road is open or not, better to ask locals in Mossman.
For most of the year this is the way to get further north. Drier, less rainforested country.
South towards Townsville
Option 1 Both Mulgrave Road and Bruce Highway can be hitchhiked a mere 5 minute walk from the city. Don't expect a ride all the way, but it is a good and easy way to get out.
Option 2 Get to the bus station on Lake Street in front of the Woolworths. Take a bus ride to Gordonvale ( $5.20 ). From there walk past a bridge and hitchhike right after the bridge. Or, perhaps a better place for cars to stop is before the bridge, just after the traffic lights. Here cars are going slow enough, and have plenty of distance to see you and stop. The bus turns right at these lights, after going through town. You want to get off here, it's the lights where the bus turns right onto the highway to go back in the direction of Cairns - this is as far as it will take you in the direction you want. Just ask the driver about the stop, he will let you off at a convenient place. It took some anonymous hitchhiker 15-20 minutes to get a ride from there straight to Townsville.
Sleeping at the airport can be slightly annoying as it shuts at night and security guards sometimes do rounds.
Other useful info
Cairns has free internet in every tourist information office, tour sales offices and various other tourist things. It is probably the city with the most free per capita in the world.
The airport is in the middle of a swamp. The nearest place with public transport is Sheridan Road, roughly a 2 km walk from the airport on a road with a annoyingly thin shoulder through the swamp. It's normally more senseful to hitch there from the intersection of Airport Drive even though there is only limited pulling over space.