Some general advice from a regular Sharks guest
sharks is the fkk i go to the most often. i had mostly good experiences there. it's possible to walk to the club from the train station (nord is better than hauptbahnhof) , but not necessary since you can also take a public bus, and a taxi costs only around 10 euros from the train station. walking is not dangerous (i have done it at least 20 times without ever getting into trouble) and there are even a few sights on the way from the hauptbahnhof: the kirschenallee (lots of hookers standing by the street. but you'll find much better service at the sharks) and very close to the sharks there is a world war ii bunker (looks like a gigantic grey pointy penis). last time i passed by the door was open and i could peek inside. lots of living and dead pigeons, old furniture and interesting graffiti.
a few girls i highly recommend:
-lorena (tiny romanian / gipsy girl, b tits, beautiful face, dark hair, wears a lot of eyeshadow, nicknamed "pocahontas" or "cleopatra" due to her looks)
-roxana (romanian, it's not really possible to not see her. model-like body, beautiful smile, blonde hair)
-jessica (moldavian, relatively tall, dark chin-long hair, soft b tits, very energetic)
and definitely stay away from "brasilian" (=romanian) flori.