Enna is a city on Sicily.
To autostrada (Both directions)
Take the Via Leonardo Da Vinci out of Enna, either walking (a good hour) or hitching. Unless your ride is taking the Autostrada in your direction, get out at the junction before the Autostrada where there is the Madonna of the Autostrada (ask the driver!). This is technically where the autostrada begins, and it is illegal to hitch beyond this point. (Ecasalicchio got moved by the police for hitching further down before the actual ramp to Catania.)
to Caltanissetta, Agrigento and west Sicily
Go to Enna Bassa, at the most western junction, there's a crossroad with traffic lights, avoid it..keep walking west following indication to Caltanissetta you will find better places.
Up and down the city
Enna is very mountainous, public transport, unless most of Sicilian and Italian cities must be paid at the driver so there's no room for blackriding. Also locals use to hitch from Enna Bassa to Enna Alta and vicersa; walking is also an option though can be pretty tough especially with a backpack..
There's a perfectly new, abandoned house on the eastern hill, next to Castello di Lombardia. You can also wildcamp in some spot down there but if the wheather is not nice (winter might be quite cold down to 0° or minus; and all the year long it is very windy) the house, even if quite creepy at night, especially alone, is very comfortable and safe. Some teenagers use to go there, to overcome their fears, play, smash glasses and similar, but it should be very safe, plus on the first floor there's a room you can also lock! a perfect free hotel. Water is out, some fountain around the castle.
Other useful info
Police seem pretty hot on the legalities of hitching around here.