It can be difficult for anyone to communicate with someone they don't know. I think it depends a lot on who you are talking to. For example, for some people they might not like it too much being asked their age or if you asked a guy if he has a girlfriend, it may seem you are wanting more than just a conversation. I suggest you try to mix up telling them stuff about yourself with asking them stuff too. You can try to use what's around you as things to talk about. If there is a sports game on the TV, you might ask if they are interested in that sport, then what other sports they like, whether they get to play it much, etc., all the time sharing a bit about yourself. Maybe talk about the music, ask them if they are here alone, if they come here often, what they do, how long they have been in China, etc., but just remember you're not interviewing them, you want a conversation.

in my opinion, it's not so much about 'communicating with foreigners' as trying to connect with another human. just treat them like a new person and get to know them. don't worry about what you talk about, let the conversation unfold how it does...