How to know if he's into you or not?

[Summer Nights]

There's this guy. He seems really cool and is just my type. And I really wanna impress him and get to know him.
So i went online and searched about how to impress a Leo man (he's a Leo). It says that Leo men have very big ego, so they will not just tell you how they feel or even be so obvious about their feelings.
He seems to be interested in me when we hang out in groups (smiles a lot, looks at me frequently...) but when i text him or talk to him on facebook, he replies slow and doesn't ask questions, seems like he's not interested.
I've been told that if a guy's into you, he will find a way to talk to you, no matter what. So i'm really confused cuz one minute he's like this, and the next minute he's like that.
I just don't know if he's the kind of guy that's afraid to express his feeling when he's not sure what the other person thinks about him (cuz i'm very careful too, i'm not obvious so i'm afraid he doesn't know how i feel about him) or he's just not that into me.
I like him but I'm so tired of having to think so much. My friends tell me to give up ) But I don't want to.
What should i do?

[183]

You can know if he's into you or not, by seeing his behaviour when he is around you.