Even if you are naturally shy, these three tricks will help you to quickly build a new social circle in any new city.
1. Take pictures
    One of the great things about taking pictures at an event or a party is that it gives you an excuse to get in touch with the person later. Everybody loves seeing pictures of themselves, and it's very easy after taking a picture to say “If you'd like I can email it to you”. This can be the seed that leads to new connections.
2. Eat alone in public
    You might feel self-conscious eating by yourself but it has an important benefit: you are much easier to approach(接近) when you are alone. People may be afraid of disturbing you or being rude if you talk with someone else. Bring a book or newspaper to read. Plus, having an interesting book with you will give others an excuse tostart a conversation if they've read it.
3. Join a class, sports team, or club
    Yoga, salsa dancing, volleyball, Toastmasters (a public speaking club), a class for work, etc. Choose a new hobby or continue an old one!
These are all great places to meet new people, primarily because you will be made to see the same people over and over again in the class. You will automatically make friends with them if you have a common interest and are made to see each other again.