This is very difficult. Not only is it difficult to enter Hengdian, but even if you do, the crew will prevent you from entering the crew to find a star. You can wait in the biggest hotel outside Hengdian, because most stars will stay there when they go to Hengdian for filming, but they can only wait, because the hotel staff won't tell you the star's room number, so it depends on luck whether they can wait until Liu Shishi.