Well, you could try wearing an impressive costume that catches people's attention. And when you see a girl you want to talk to, compliment her costume or ask about her favorite comic characters. Just be genuine and confident.
You could join a group or panel discussion related to a popular comic. That's a great way to meet like-minded people, including girls. Start by sharing your thoughts and listen to hers. Also, don't forget to smile and have a positive attitude.
Wear an eye-catching costume or carry something unique related to your favorite comic. People might approach you to talk about it. Also, look for communal areas or lounges where people are hanging out and introduce yourself.
One way is to attend panels or autograph sessions where actors are scheduled to appear. You can also try waiting near the entrance or exit of the convention center where they might pass by.