The best way I've seen it implemented was a museum that not only had a lengthy explanation about how to turn off your flash (including examples for Sony point-a

The best way I've seen it implemented was a museum that not only had a lengthy explanation about how to turn off your flash (including examples for Sony point-and-shoots, which were fairly popular), but also had a "test table" with similar light as you'd find inside, so experts could adjust their exposure/ISO accordingly. Perhaps that's expecting too much from the average tourist, but still, I found it cool.