(from earlier today...)

Me: Okay, let's meet at my place at 22:00. We'll walk from there. You should probably dress sexy. ;-)
Her: Hey, watch yourself! :-)
Me: No, don't think that I will. :-)

If she asks:
Her: "Why?"
Me: "Because that's what I like." or "Why not? :)" etc.

It's playful, it's sexual, and it's not so overboard that you can't use it for second or even first date. Also good if you're afraid that she might think that you two are "just friends".

Later you can find out if she made the effort for you (she IOIs you). Or maybe you neg her when you meet because she didn't sex it up enough (even if she did!). Or if you want to send an IOI her way, you can comment that she pulled it off.