Use the opportunity, while you're on your way, to add accidental contact with strangers, whether they are locals or other foreigners that you meet, to your list.
Most people sort strangers into categories - male, female, white, Asian, old, young etc. Rarely does anyone recognise a stranger on the street, in a queue or elsewhere as another human being.
Interactions between strangers is different between cultures. And while some don't want to obtrude on the privacy of others in any way, others find it uncultured to not greet someone on the street.
Whether you are someone who can easily make contacts or not, we suggest that you add interactions with strangers to your to do list in Belgrade. Smile at a passerby, start a conversation about a thing both of you are attending or experiencing or give a compliment if you like someones coat or shoes, for example.
You never know what you can find out from that interaction or how it will contribute to your day or your experience as a whole.