SHUTTERBUG-loving socialite Tinsley Mortimer was teaching fellow guests at a dinner party how to pose for cameras – especially when you have something to sell. Mortimer revealed how she pimps her handbag line for Samantha Thavasa in Japan. “I hold it in front of me and try to be natural, so the logo shows,” Mortimer said. “It works. It ends up in all the Japanese magazines. But I try not to be too obvious.”