What cultural faux pas should I try to avoid making in Potsdam?

"In Potsdam, it's considered rude to be late for appointments or meetings, so always strive to be on time. Avoid discussing World War II and the Holocaust unless it's brought up by someone else, as it's a sensitive topic. It's also considered impolite to chew gum or eat in public places like on the street or in public transportation. When dining, remember to keep your hands on the table (but not your elbows), and always say "Guten Appetit" before starting to eat. It's also customary to wait for the host to start eating before you do. In Germany, it's considered rude to interrupt someone while they're speaking, so always wait for your turn to speak. Also, avoid making loud noises or speaking loudly in public places, as Germans value their quiet and peace. When greeting someone, a firm handshake is the norm. Germans are generally reserved and may not appreciate hugs or kisses on the cheek, especially from strangers or casual acquaintances. Lastly, remember to respect the environment. Littering is frowned upon and recycling is taken very seriously in Germany," mentioned another expat when asked about moving to Potsdam, Germany.