How to get closer to a guy?

Okay, so there is this guy who goes on my school bus. He's three years older than me, but we know each other, mainly because one of his close friends gets off at my stop, so we (his friend and I) know each other quite well. I never realised I liked him until a couple of weeks ago. Before, when I didn't like him, I used to be comfortable around him, and didn't have a problem with glaring at him etc. if he ever did something really boyishly stupid (really I found it funny, but I'm supposed to be the mature one in our group!). Anyway, there have been a few incidents with him-well, not really incidents, but in my stupidly infatuated mind that's what they are! For one thing, every single day when he gets on the bus (he gets on after me), he always makes eye contact-I am not kidding! Also, I've seen him around school a lot, and he also hold my eye then as well. I don't know if it's all in my head or what...there were some other things too, but I don't want to go into it now. My question is, basically, how do I get closer to him, or even strike up a conversation with him without being totally obvious!! (I'm quite a shy person, so keep that in mind!!)