Nantes is a city in western France of roughly 600,000 inhabitants.
North towards Rennes
Take the tramway number 2 and get off at "Le Cardo". 20 meters behind you you will see the road going to Rennes. This is a very famous spot which works very well. Cars have place to stop and as there is a roundabout they are not going fast yet.
West towards Saint-Nazaire, Vannes, Brest
There is a nice spot at the commercial center Atlantis. You can reach it with the tramway number 1, get off at the terminus "François Mitterand". Once there, you follow the railways until the next cross-way (20m), there turn right. On the third roundabout is the sublet to the N444. The walk might take you 5 to 10 minutes. Be careful, this spot doesn't work on Sunday. Cars taking this sublet are either people who get home from work at the industrial zone or people who went shopping in the commercial center. On other days of the week it's a good spot. You can be seen and cars have space to stop.
Take the BusWay (line 4 of tram network) to Bourdonnières, cross the carpark and wait at the small roundabout, on Boulevard de Vendee. The first petrol station leaves you on the A83, the motorway towards Niort.
- Take the tramway number 1 and get off at "Bd de Doulon". Down the street "Boulevard Doulon" and go to the roundabout at the junction with the Boulevard de Sarrebruck. There you can start hitchhike, you can be seen and cars have space to stop.
- Take the tramway number 1 and get off at "Haluchere". Cross the tramway rails: the road ahead is Route the Paris, the old road to Paris. If you don't go further then Angers, you can try on this road: you will find cars at the Leclerc petrol station (see below). For more distant destinations, it is better to take the highway at the junction 4 km further on Route de Paris. To get there, you can walk (about 1 hour), or take bus number 78 to Cifam or 85 to Bel Air (pay attention to timetables, these buses don't always work). But the best is to find a ride until there from the Leclerc petrol station. Start walking on route the Paris. Soon you will see a Leclerc supermarket on your right side. The petrol station is in front of it. You can try to find cars going on the highway, but this is rare. Instead, you can ask them to take you to the junction 4 km further. Once you are at the junction, stand at the red light in the middle of the road, in the lane which turns left towards Paris. The cars turning here go all on the highway.