Varna is in general safe also at night.
Hold your drink. Bulgarians do not accept drunken behaviour. If too unruly, you might get arrested.
Careful when swimming. There are currents and sometimes high waves. Red flag means no swimming. Yellow flag – be careful. Green flag – safe.
Ask for advice. Bulgarians in general are friendly and try to help.
Shake/nod: In Bulgaria “yes” is a shake of the head and “no” a nod.
Home invitation: It is not very usual in Bulgaria to invite unknown persons. Usually people meet outside in cafés and restaurants.
Restaurants: When ordering food in a restaurant you need to order garnish separately, for instance potatoes, rice etc., in addition to the main course.
Fried potatoes are served with or without cheese (they will ask).
Cheese: In Bulgarian there are two words for cheese: “sírene” сирене – white cheese and “kashkavál” кашкавал – yellow cheese.
You ask for the bill with “smétkata, mólya”. Round up the payment if you are satisfied.
Be polite. People appreciate politeness. Everywhere.