Ok, female point of view:
In my experience guys are really quite straight forward in adressing how they feel.
Meanwhile girls are really quite retarded in this area, we tend to flirt with people we dont like and ignore or act awkwardly around the ones we do.
Anyway just try act natural, and ask him the simplest of simple questions "so [insert guys name here] do you like anyone at the moment?
I know it sounds SOOOO yr 6, but you will be able to tell if he is interested in you at all by his responce.
Last time i asked that it prevented me from making a huge mistake as the guy went " oh so youve noticed!! So tell me would it be a wise ideas to ask [girls name who is not me] out? ..." he then proceeded to spill his guts, and it ended in him saying "Thnx, ur a great friend"
at that moment i knew that i didnt even like him either ... sometimes the lack of eligible guys makes you think you want to go out with a friend... but in reality you just want someone like them.... but not them...
Sheesh did that make sense?
Just think about it, do you like him? Or just the thought of him? Can you see your self having intimate/sexual moments with him? or simply do you see him as the kind of guy you just want to spend the rest of your life with? IS there any physical attraction? Or only his personality?
Now this may sound wrong, and you may say "well all that matters is his personality" ... well when ur going out with someone... no, thats not all that matters, if it is you are deemed to stay friends, and only friends.
Hope that helps.