Ah...aproaching women. I could teach classes xD I'll give you hand buddy.

I think firstly that your jumping the gun - you can't really "make a move", being that you haven't even spoken. What you need to do, is make sure she knows you and make some sort of rapport.

The easiest way to do this if your not comfortable with just a confident walk-up-to-her-and-start-chatting approach, try building comfort through passing jokes. As an example;

Last weekend I saw a pretty hot girl who I wanted to talk to. About 5 minutes later I saw her stood by herself, her friends had walked off. I could have just gone over and spoken then...but I chose instead to walk past her (on my way towards another group of friends) and just look at her and say, "Whats the matter? Not got any friends?". Delivery is key. I smiled and laughed, but kept walking. She laughed back and I continued talking with other friends.

10 minutes later I return, and shes still stood by herself. So I walk over, laughing still,
"Bloody hell, still not found any friends? I'll stand with you - otherwise I'll look bad for ignoring you". She laughed and we started talking straight off (got on REALLY well )
I was insantly accepted 'cos I already had a running joke with her, even though I hadn't even met her properly.

Read a situation, somewhere where you could just make a little joke at her expense and then carry on with your normal activities. Strangely, small doses like that keep you in her memory - making you remembered as that "funny guy who insulted me for having no friends :P' or something similar. It also makes her wonder who you are...and hey, chances are, she'll start the next conversation to know more.

Be friendly, funny. Get her to notice you. Then Introduce.
Then make a move.

Girls finding out a guy "really likes them", yet she has never really spoken to him, prety much kills the chance. 'cos her reply will be "Who?". Make her know exactly who you are

Good Luck.

/Riot.