I've known this guy for 3, almost 4 years. When we first met, I had a boyfriend and we all hung out in a group. After the break up with him, I kind of avoided the group, and didn't join again until after I had gotten a new boyfriend. In the past few months he's become more and more flirtatious. He would even make comments asking me why I was dating my then boyfriend. I took this as odd because he never made these comments when I was dating my first boyfriend he knew (who was a major loser). I asked my brother (his friend, met through me) if he (our friend) seemed 'friendlier' lately and he said it was because he was proud of me. (I started getting my act together (instead of being a stupid twenty-something), starting going to college, started my own business and such). So I ignored it for a while.

My boyfriend and I broke up about a month ago and I've started to like my guy friend and notice him more. I've noticed things he does that makes me wonder if he likes me.

Like when we hang out in groups, he's catching my eye a lot and smiling. Especially when he makes jokes. He teases me a lot more, he steals my food sometimes (he used to never do this, even when I was offering food to the whole group), and he's become more touchy. Like he'll pat me on the head (he's over a foot taller than me, this has become amusing to him), and he's asked me about stuff like how an outfit looks on him (for an interview) and help with a school assignment (detailing his strengths).

I've pretty much become convinced that he likes me, but some things still make me wonder. Like I invited him to go hiking (only him, though I didn't tell him I was only inviting him) and he invited his roommate (also my friend), we don't really text much (but he doesn't text much at all, didn't have a cell phone until last year), and stuff like that.

He hasn't had a girlfriend in the time that I've known him, so I don't know how he acts around girls he likes, and I don't know if I'm only noticing these things because I like him.

I would love to start dating him, but I don't know how to approach it and I want to know if he likes me first. Any sure fire ways to figure it out?

Okay, so, there is this thing called the dare game. You get one of your friends to go up to him and say "Do you want to go out with -what ur name is-" and then if he says yes, you got a boyfriend if he says no then tell your friend to say "ok, thats all goods, this was a dare anyway!"
Hee hee, I've done it before, but he said no. :( thank god I don't like him now

How old are you? You are posting on an adult board, advice which is juvenile, same advice more than once.