Okay so I Iike this guy..? (Guys I would like you input too)?!

I like this guy but I don't know if he likes me. I always try to text him, well after like a week and a half will go by I will, but he will never answer. Sometimes he will text me and we will have nice conversations and other times he will never even text me. This other girl likes him too, which makes my girl hormones shoot through the roof, and he says he likes somebody but he won't tell who. So basically, how do I approach him and ease our way into a conversation, what are topics that we can talk about, and how will I know if he likes me?