Bulgarians are incredibly friendly and very interested in talking to foreigners. Bulgarians tend to be much more open than some other Eastern Europeans and it is very advisable and useful to engage in dialogue with them. In small towns, especially in the Rhodope Mountains, people may invite you to lunch or even spend the night at their home. It is often a nice gesture to give someone a “Dobar Den” when you pass a quiet stall or person. Kak ste (hello) is usually enough for the younger generation.
In general, in most countries of the world, you should avoid topics related to politics and foreign relations, and sometimes football. If you are involved in such a conversation, try to remain neutral. Remember that your own knowledge of the local conditions will probably not be as good as that of a Bulgarian!
For some people Macedonia is a sensitive topic, but you are welcome to ask your questions as long as you do not talk about it with those who might be more likely to take offence (e.g. nationalists and skinheads). Many Bulgarians believe that Macedonia belongs to Bulgaria, but if you don’t know the subject and the people you are talking to, it is best to ask questions.
Most Bulgarians do not feel anger or resentment towards Russians (unlike a number of people from other former Eastern Bloc countries), and Bulgarians tend to perceive Russians much better, but caution is sometimes needed when discussing issues concerning Turkey. Similarly, there is discrimination against Turks and Roma, but this is mainly due to certain nationalist groups that are not very different from the hate groups in Central and Western Europe.
Bulgarians don’t really gossip, so trying to strike up a conversation with someone at the checkout in a shop will probably result in strange looks (either because they don’t understand or don’t want to get involved) or they will just ignore you. Also, Bulgarians are quite impatient and will often honk if you run in front of a car, especially in winter in the mountains where they try to keep control of the road.