She called me, so how do I proceed now?

As some of you no doubt know, I have asked a couple of questions on here about a girl recently.

On day one we went out, she flirted with me, I flirted back a little, and we had a good time.

Day two we meet up, have a good time, I tell her I am interested, and she says she is not. The evening continues just fine, and we end up making plans to meet up again.

Day three, as per plan I call her to see if she wants to do anything, but she says she already has plans, but insists I should call her again another day.

Day four, five, six (or how many others there have been since) I go about my day without calling her.

Today, she calls up.

I told her I could not meet her today, there is a guy sick at work, so everyone is chipping in to cover his hours, but I told her I would call her again tomorrow or as soon as I know what I am doing. This was no lie either, with the time I had today, I honestly did not feel like it.

So… Tomorrow I call, we go out some time soon again, and then what?

Do I just take her out for a good night out? do I mention the whole topic of relationships again? I’m at a loss.

My instinct would be just to take her out for a nice night and see what happens. However it would be nice to know what she is thinking.

Any Ideas?