Not laughing at tourists is hard. Being nice directly to their stupid face is even harder. But they’re having more fun than you. And you were a tourist once too or maybe you still are. So be nice.
Just because you live here now, or know how to do XYZ that said tourist sucks at, doesn’t mean you’re bigger and badder than they are. Nobody starts anything with experience so be the bigger person and lend a hand. That means taking their picture instead of letting them take a selfie. Please take the selfie stick away from them.