how to make a friend with a foreigner

I am from the UK, and understand why you worry about 'breaking the ice' with people from abroad. Whreeever we were born, we are raised with an idea (often wrong) of what people from another country are like. This may seem strange to you, but many people in the world think Chinese people are very formal and quiet, but I'm sure you know many friends who are chatty and outgoing. My only real advice that I can offer you, is to just go over to the person, when they don't seem to be busy with something else, and say hello, introduce yourself by name, and politely ask about where they are from originally. An example, would be to say, 'Hello, my names Glen, and I noticed that you were speaking English (or, I noticed you seem to speak Mandarin with a strange accent,), do you mind my asking where you have come from originally?'. Certainly, with a European person, if you were to wear a warm & welcoming smile as you asked this, there would be no offense taken, and once there original locality was known, you could ask about their homeland, and how they are finding life in China, before moving onto subjects like sport or films. People would only be a little upset,, if your manner seemed aggressive, or if it appeared you were implying that they shouldn't be in China. The smile will help dispel this problem. Good luck, be brave, and if it doesn't work with the first person, please try again. I hope to come and work in China, myself, in the not too distant future, and would greatly enjoy it, if a native Chinese citizen were to engage me in conversation. It would make me feel accepted, and welcomed. All the best.