Bulgaria is a very safe country to travel in comparison to other countries in Europe whose metropolises attract crowds of tourists. It is often in popular traveler destinations that people will wait for those new to the area to let their guard down. Here are some tips that you can use anywhere you may go in the world. These will help you not to draw the wrong kind of attention on your vacation.
Rather than a backpack, instead invest in a tough cross-body small bag. Ideally, when you keep the body the bag close to your body, no one will be able to try and pickpocket you or take your belongings. Some people will suggest wearing a backpack backwards, but this does not look natural and would most likely alert others of your foreign-to-Bulgaria habits. Also be aware of what others are wearing. Although your flip flops may be comfy and convenient to pack, you may find that in comparison to the United States, most other developed nations appreciate at least crisp jeans and a top that is a bit nicer than a t-shirt (like a knit top.)
When it comes to walking the streets in a new place, we would advise not doing so alone. Travel insurance is a worthwhile purchase when going abroad. You may know to watch out for suspicious alleys and areas that are not lit well, but having another person that you know can help you to make more informed decisions. We hope to see you soon in Varna. Safe travels!