Be open minded and just keep smiling. No girl likes to meet a guy with a person who smiles rarely. Be natural and do not make a show that you are looking for girlfriend. Try to talk to the girls more so that you can know more about them and they can know about you... just cheer up.
The best secret to finding a girlfriend is to exude confidence without being too arrogant. Women like a man who is confident. Even if you are having a day that you don't feel your best, fake it!
You will find a girlfriend faster if you start hanging out with one of your friends and his girlfriend. Her single friends will be around and she will be able to help break the ice.