If you aren't with her yet then you aren't really in love with her, you just like her a lot. You'll know the feeling when you finally feel it though. Believe me I thought I was in love a few times but in hindsight I wasn't, I was just attracted to them.
As for trying to get their attention, if you're already friends with them then you shouldn't really have a problem talking with them. The key in my opinion is to treat them like a person, and not to be too forward with them about your own feelings. I've found that girls are much happier to hang out with you when you're not constantly hitting on them, thats why guys in relationships feel like they suddenly become more popular with girls, I definitely did. They're attracted to someone who isn't constantly trying to get in their pants because they feel like he's open or genuine or whatever, but really he's just trying to avoid invoking the wrath of his girlfriend.
I'm not saying to pretend you're in a relationship or to pretend you don't like her, just treat her like a friend and a person, if she ends up liking you back then great, if not then it wasn't to be.
Aaaand upon reading the question I realise you are a female. Well if you ever bend the other way my advice is above. Anyways if you want a guy to like you just befriend him and ask him out, we're really simple creatures, not that socially complex, subtle signs will NOT work most of the time. The amount of "horror" stories on reddit of guys who have looked back on an encounter with a girl and realised that she wanted more and he never realised are astounding. Just be straightforward with a guy, if you're friends then just tell him what you want and see what happens. If not then get to know him a bit before dropping the question, just in case he is secretly a giant douchebag.
but in other words it all depends on the person and how "confident" they are
