Friedrichshafen is a city in Germany. It is situated at the Lake Constance (Bodensee) in Southern Germany, near the borders with Switzerland and Austria. It is the district capital (Kreisstadt) of the Bodensee district (Landeskreis) in the federal state (Bundesland) of Baden-Württemberg. Friedrichshafen has a population of ca. 58,000.
The gas station close to Edeka in the "inner city", right by the harbour, has proven to be quite a good starting point for anything along the B31 going East.
Continuing further on, if you follow Eckenerstraße until it becomes Lindauer Straße, there's a nice area for waiting, by a carpark and a zebra crossing, and many cars here will be joining the 31/E54. dragonkillernz was there for around 20 mins before getting a ride (although only as far as the Aral petrol station just off the 31 near Kressbronn...not recommended!)
Once you get to Lindau you can get on the Autobahn towards Munich or South (Austria, Italy) quite easily from the roundabout (Aral station, Mc) where the B12 stops and the A96 begins.
South-East towards Ravensburg
Leaving either the railway station (Friedrichshafen Stadt) or the ferry terminal you can find signs that lead you to the B30 (in direction Ravensburg). You can walk out of the core of the city along the B30 and find either bus stops to stand at or free parking spots where cars can pull in. Unfortunately, there are no ideal paved shoulders once you reach the end of the city.
North-West on B31 towards Meersburg , Konstanz and Uberlingen
The B31 and B30 are the two major roads that run by Friedrichshafen and it is the B31 (direction Meersburg or Uberlingen) that you want. Either follow road signs on either of the B roads or walk with the lake on your left until you find a road sign to follow. Go along either of the B roads until they join together and become just the B31. After this point you should walk along the road a few hundred metres further and you will find a bus stop that offers a good place to hitch from. Be sure to have a sign with you and stick your thumb out as well so that people don't just think you're waiting for a bus. Waiting times usually only 5-10mins. If you are traveling to Konstanz, get a ride to Meersburg and take the ferry across the lake.
Or you go to the small gas station next to the "Landratsamt", that's also at the spot described above where B30 / B31 converge, but might be better than a bus stop since you can talk to people.
If you are in the Fischbach area of Friedrichshafen you should walk out of the area along the B31 in the direction of Meersburg and you will see a large spot where cars can pull over. This can be a road that cars drive fast along but the spot is large enough for them to slow down and pull into if they want to stop for you. Waiting times usually only 5-10mins.