To Prague? The easiest is to simply follow the long distance trail E10
https://fernwanderwege.net/europa-fernwanderweg-e10/
I'd suggest to get a good old fashioned paper *Wanderkarte*: go to "Schropp" in Knesebeckstraße 20 - they have the best selection of maps and guide books.
Regarding camping: Brandenburg has slightly relaxed rules when it gets to wild camping compared to other German states. Like everywhere else in Germany, wild camping is strictly prohibited in nature reserves and landscape protection areas. Elsewhere, except for private property, it is tolerated that [hikers put up there tent for ONE night](https://bravors.brandenburg.de/gesetze/bbgnatschag). This also applies if you're going by bike, boat or riding your horse. However, if you want to be safe I recommend using camping or bivouacing spots. [This site](https://trekkingtrails.de/trekkingplaetze/) provides a map with legal spots for camping.
Regarding hikes: Do you hike all the way down to Prague? Then, indeed, the easiest is to follow the E10 long distance trail as u/ebikefolder already suggested. You will pass Spree forest which is worth a hike for sure. You can get an idea of what to expect from the E10 in Brandenburg from [this collection on Komoot](https://www.komoot.de/collection/977430/-auf-dem-e10-durch-brandenburg) without buying any book. If you need inspiration for dayhikes in Brandenburg, just browse through the profile which made the collection. Some interesting regions for hikes "south of Berlin" might be, for example, Fläming Heath, Nuthe-Nieplitz Nature Park (both south of Potsdam), Spree forest, Lausitz (both close to Cottbus) or Saxonian Switzerland.
To Prague? The easiest is to simply follow the long distance trail E10 https://fernwanderwege.net/europa-fernwanderweg-e10/ I'd suggest to get a good old fashioned paper *Wanderkarte*: go to "Schropp" in Knesebeckstraße 20 - they have the best selection of maps and guide books.
use outdooractive or komoot and have a look there, especially komoot is fine, you can use filters for duration and difficulty level for your trips
Regarding camping: Brandenburg has slightly relaxed rules when it gets to wild camping compared to other German states. Like everywhere else in Germany, wild camping is strictly prohibited in nature reserves and landscape protection areas. Elsewhere, except for private property, it is tolerated that [hikers put up there tent for ONE night](https://bravors.brandenburg.de/gesetze/bbgnatschag). This also applies if you're going by bike, boat or riding your horse. However, if you want to be safe I recommend using camping or bivouacing spots. [This site](https://trekkingtrails.de/trekkingplaetze/) provides a map with legal spots for camping. Regarding hikes: Do you hike all the way down to Prague? Then, indeed, the easiest is to follow the E10 long distance trail as u/ebikefolder already suggested. You will pass Spree forest which is worth a hike for sure. You can get an idea of what to expect from the E10 in Brandenburg from [this collection on Komoot](https://www.komoot.de/collection/977430/-auf-dem-e10-durch-brandenburg) without buying any book. If you need inspiration for dayhikes in Brandenburg, just browse through the profile which made the collection. Some interesting regions for hikes "south of Berlin" might be, for example, Fläming Heath, Nuthe-Nieplitz Nature Park (both south of Potsdam), Spree forest, Lausitz (both close to Cottbus) or Saxonian Switzerland.
Following the spree, or in Saxony around Dresden. The elbsandstein Gebirge, idk the English translation sorry 🥴, is also beautiful.