<map lat="49.129688444873" lng="6.1868852376935" zoom='11' view='3' float=right/> Metz is a city in the northeast of France, capital of the Lorraine region and préfecture of the département of Moselle (57).
West towards Paris (A4)
There's a bus that takes you all the a way to a highway gas station. However, it runs only once an hour on weekdays, and only if you telephone-call them on weekends and holidays. The call-for-bus scheme involves registration and you have to call one day before, so you're probably better off riding the L3 bus to Woippy (a busy line) and walking-hitchhiking the D4 north-west if it's Sunday. Get off when it crosses the highway and the gas station will be staring straight at you. All the way on foot from Metz took 3 hours.
On normal days, take bus 106. Get off at Champ Banal (ask the driver to announce the stop for you). From there, walk the same way the bus left, towards the highway almost up to the very intersection and right before it take to the right onto a dirt road on the side of a field. Walk this dirt road alongside A4 and you'll see a service station around 500 meters ahead.
Bus 106 PDF timetables and map (figure out which station is near you with this)
Whatever you do, don't get dropped off where the A4 (east/west) meets the A31 (heading south towards Metz).
North towards Luxembourg, Brussels, Trier
Take bus number 111 to La Maxe. The ticket costs 1.50 EUR. Get off at the stop Goujenotte beside the massive IKEA shopping centre and walk down the road until you see a roundabout and an ESSO service station nearby. Walk down the ramp until you reach both of the exits. One hitchhiker got a lift within 10 minutes while standing between the ESSO petrol station exit and a motorway exit. There is a lot of international traffic in this region.
Take the bus number 111 direction La Maxe from for example Boulevard Poincaré (right by the river, about a 10-minute walk from Place de République) and go to the last stop (the ticket is 1,50 EUR). From there walk west, walk over the motorway and walk further on the same street around 2 km until you see a petrol station. When you see the petrol station, it is better to walk about 500 metres further and walk into the station along the motorway (there's a little path that will bring you on the motorway). From this petrol station, it is easy to get rides directly to Lyon or even further.
East towards Saarbrücken, Frankfurt or Strasbourg
From Gare SNCF (the main train station) or Place De La République take the bus number 8 or U to Technopole (both stop next to lake Symphonie - ask the driver). From there walk to Grigy (part of Metz). Once in Grigy, keep on walking along D955 outwards the city center (follow the signs to Strasbourg). The road goes slightly uphill on top of which there's a roundabout right before the short bridge over the motorway to Nancy, then another roundabout. Stand just right after the second roundabout (one hitchhiker tried three times there and never had to wait for more than 20 mins). If you go to Germany make a sign for Strassbourg and then get off at the peage which is about 30 km away. You can also make a sign saying A4 Est Peage
This spot next to the bridge of Rue Du Général Delestraint over A4 map If you use a sign saying A4, make sure the driver is not going north towards Paris (learned the hard way). Try to get a ride to one of the rest stops on the A4. Aire De Longeville-lès-Saint-Avold Sud rest stop is the biggest on the way (with free wi-fi and showers) from there, you will find many truckers going towards Saarbrücken.
North, West or South (Luxembourg, Paris or Nancy)
It is possible to get a ride towards these three different directions by standing on the Avenue Joffre, under the bridge, in the western part of town, very close to the city centre. It merges with the A31 300m further. Always use a sign here. Hitchhiker experience [Jass] - this place is useless...there's very little time to stop and the road is already fast. Just take the bus - after 3 hours waiting, it's worth the bus fare, even if one never takes public transport. Hitchhiker experience [linux2400] - I agree with Jass, also waited several hours there. Then I walked east for about 100m to the roundabout in front of Chambre de commerce et de l'industrie and got taken pretty rapidly, so this is the spot I would recommend if you want to start from downtown. There's red lights and places to stop and all the cars end up on the motorway all the same.