I need some real help here?!?

So i'm 17 years old and have only had 2 bf's when I was younger. I was around 12 and 13. So I don't have a lot of experience with guys. We are going to a banquet soon and there will be a guy there that I like and he likes me or atleast he used to. Every year when we go he talks to me..So what should I talk to him about? I wanna make conversation and be flirty. Keep in mind that i'm shy sometimes. Also we missed it the last few years so I never got to talk to him because I never see him. So what can I say? Like I said, I wanna be flirty and make conversation. He is mature for his age i'm sure!