How: in fact, the same way like wherever else, I believe. Keep your wallet closer to your body, and your cryptowallet even closer, don't play games you don't know the rules for, don't try violating the local laws (even if your "new friends" guarantee that everything gonna be ok). You can have drinks and dating (if know the right place to search) but don't try to buy drugs, even weed - local prisons are of somewhat much lower standard than abroad. And consider keeping as far away from Russia-controlled regions as possible.