Bulgaria is generally a safe country, and people are quite friendly. You should however use common sense when you are outside of the main tourist areas, i.e. don't show off that you have money, don't dress too touristy, watch out for your belongings. If in Sofia, try to avoid dark streets at night. Stepping in a pothole is a much greater danger in Bulgaria than getting robbed.
Emergency phone numbers
The pan-European standard number 112 for all emergency calls is working everywhere in Bulgaria since September 2008. If, for some reason, you can not connect to 112, dial 166 for police, 150 for ambulance and 160 for the fire department.
Driving
Driving in Bulgaria can be "nerve-wrecking", as in any foreign country. There are a few modern highways. Some roads are in poor condition and full of potholes. The use of seat belts is mandatory in Bulgaria for all passengers, except pregnant women. Take caution while crossing the streets. Driving with your headlights ON is mandatory even during daytime. If you are caught driving without having your headlights on during daytime, you could get a ticket. The fine is €25 (or 50BGN), so be sure to turn your headlights on. In case you get caught, explain to the police officer that you are a foreigner and you weren't aware of this law and let them know it won't happen again. It is very likely that they will let you go with just a warning.