What to do if a girl comes up to you, but does not initiate talking

[aphoria]

I go out alone and I don't approach woman. Yesterday it felt like this girl is interested in me, but I didn't do anything yet I liked her, so I am looking for tips what I should/could have done.

A girl comes up to me on a dance floor, she stands right in front of me, looks at me and then immediately goes away. All that happened so fast that I only managed to take a look at her.
1) Why did she leave? Did I make her feel uneasy?

Some time later I noticed her dancing with her friend and it seemed like they are occasionally looking at me. Then this girl comes my way and stops right in front of me (this time with her back towards me), she stands here for a moment, then turns her head around, we make a brief eye contact, she turns away and soon goes back to her friend. This sequence repeated once more.
2) I probably should have done something, but not sure what? Since she has turned her back towards me it doesn't feel natural to either touch or say something.

Some time later they end up dancing near me. I look/smile at her, but she looks right past me with blank face.

 

[Yliaster]

 

[hebbewem]

You talk to her

 

[Deleted member 16801]

u missed ur chance beacuse ur a pussy and dint make a move

 

[MostGLSlayer]

Do what I do, say "yoooooooooooo whatsup"

 

[Doober]

That's like the only real sign any girl will ever give. However no matter how much she liked u she still could reject even saying hi to her. They are weird what can ya do

 

[Deleted member 18045]

Schrezophenia

 

[Mik]

Slap her