During the WeChat scene, you'll ask the girl on a date. Before you do this, check Twitter using the tabs on the left. Doing so will show the boy that she's interested in seeing a spoof of Sherlock Holmes. After asking her on a date, she'll ask you to pick a movie, and the mystery film will be an option. If you don't check her Twitter, you'll only have three options that all net the same response and void the achievement. Be sure to pick the mystery film.
As for the restaurant, I'm not sure what I did to unlock the correct option, it was available to me and I guessed it on my first try too. She likes Hot Pot, which you can find out on her Twitter. However I didn't even know you could check her Twitter the first time around. Instead, I got a perfect score on the restaurant mini-game. I'm not sure if that was required, but checking both her Twitter and getting that perfect score would probably both work I imagine. Once the movie is over, be sure to select the Hot Pot option at the top left of the dialogue box.
The achievement should unlock as the hand-holding scene loads in.