|Motorways:||A1, A4, A7, A8, A9|
From the city center, take the metro #2 (green line) towards Cologno or Gessate. Get out at Gobba.
East towards Verona
If you want to go eastwards direction Verona (A4) try this: At the end of the platform of Gobba, right where you get out of the train, begins a bridge over the motorway leading to an extra train going only to some certain hospital. It costs you ~ EUR 1,20. Getting out there (at the hospital), you follow the stream of people and go up the first steps you see (round ones). Look for a high place - from there you can see the petrol station. Best is to ask someone to show you the best way down to the petrol station.
An alternative and easier option is to take the metro (green line) to Cologno Nord. It doesn't really matter which exit you leave the station by, as long as you are walking north. Follow the road for about 5 or 10 minutes until you get to the beginning of the bridge over the motorway. Rather than actually crossing the bridge, you turn right, off the road, and walk along the raised grassy area beside the motorway. After 4 or 5 minutes you will have reached a gas station.
Southeast towards Bologna
Walk for around 10 minutes from Porto di Mare metro station to the petrol station (also Agip) on the other side of the motorway. Look on the city map in metro stations how to walk there exactly - very simple.
South towards Genova
Take the metro to the station Famagosta. When you exit to the street, to the east you will see a bridge. This is the A7 motorway. You then have to walk a couple of minutes north parallel with the bridge to where the motorway begins. There is a traffic light and a petrol station. It is best to stand a couple of meters north of the traffic light, next to the petrol station entrance, with a sign. Cars are going slowly (or stopping at the traffic light) and there is enough room for a car to stop easily.
West towards Torino
At the end of Via Antonio Sant'Ellia (metro station QT8 on the red line) close to the park Monte Stella, there is a big slipway to the full motorway interchange between A8 and A4. So it is possible to hitch to west, north and east from there. Stand on the curb before the slipway splits with a sign. There is a street lamp nearby, so it is possible to hitch at night. N.B. occassionally there is street prostitution on the other side of the road close to stadium San Carlo.
Another good place where you can catch more westwards traffic is at metro stop Molino Dorino. There is a roundabout which splits the ramps and car park driveways. Stand at the traffic light close to Via Fratelli Rizardi with a sign. Because of the traffic light, cars need stop longer before ramping onto the motorway tangenziale ovest A50, so you have more chance to be seen and longer time for the driver to think.
Couchsurfing community is one of the biggest in Italy, you should not have problem to find a host.
The only hostel in Milan is at QT8 red metro station, but like all hostels in europe should be a bit expensive.
If you hitch at Monte Stella, there are plenty of long benches in the park and a public water tap nearby. It's a good place to stay on a summer night.
Also Parco Nord (tramway 31 or 4, taking from yellow subway zara or maciachini) can be a nice spot to camp. big enough to hide, lots of tap water. Avoid Parco Lambro (east of the city) if u can, cause rather if u can hide pretty easily some crimes did happen more than elsewhere. All other parks inside city (Giardini di Porta Venezia, Parco Sempione, Parco Solari) are closed during the night. 'Fedecicco'