Advice on how to flirt?

Basically my best friend (who is a male) was snapchatting one of his friends. That guy asked for my snapchat and now we are messaging. I have met him once and will be seeing him in several weeks for an event, but in the meantime it will have to be over snapchat. He is incredibly forward and likes to flirt but I have no idea to respond. What are some good lines which would get the conversation going and give the hint that I am interested?