Chat
You say you chat quite a bit, and that he is 'friendly'...but what does it mean?
Is the tone lighthearted, do you joke around a lot in conversation? Is he flirtatious (and if so, how do you respond)? Lots of eye contact? Is there 'innocent' touching and/or brushing against eachother? (for instance skin contact of not-overtly sexual nature; hands, arms, shoulders etc.) Are there opportunities where you can be alone with him? How sexy are you able to dress, and still feel comfortable around him/others, especially if you were to position yourself in order to let him check out your assets 'unseen'? (classic: bending over a table in order to 'read something' - that is, to allow him to check out your cleavage)
If he has a good nose, one idea can be to have yourself a really good wank before you're about to come in contact with him later, dab a little of your love juices on your neck, and then find some excuse to get close to him.
As you can tell, there are a lot of small ambiguous stuff that you can do (and not at all limited to what I've indicated above) in order to get his hunter instincts rolling, without humiliating yourself completely by throwing yourself at his feet. Be creative. Moreover, do not invest too much in getting the hoped-for result - for one, some men can be right obtuse regarding such things, while others might consciously refrain from hitting on you for various reasons (as the one you suggested yourself). I propose setting a more modest goal, like subtly working him over until he pops a boner every time you come close by. They say it can be a lot of fun for the gal, and there is always the chance of a little icing for the cake.
