During the course of every seduction, at certain points a woman's arousal will spike.
She'll go from "This guy's interesting to talk to" to "Wow, I think I like this guy."
At some other next point she'll then go from "I think I like this guy" to "Ohhhh... I want this guy."
You can see these arousal spikes (they get called 'buying temperature spikes' or 'BT spikes' in the seduction community) fairly obviously much of the time. Women will do things like:
Droop their eyelids ('bedroom eyes')
Smile lasciviously at you
Move much closer to you
Let out a little moan
Blush/flush their cheeks
Flash (suddenly raise) their eyebrows at you
Begin to touch you on their own
Let their lips part and mouth hang open a bit
Tilt their heads at you
(incidentally these are all things you can -- and should! -- do yourself as your seductions progress to create the feeling of greater intimacy and escalation)
When you see a few of these signs, it's a pretty clear indicator you're turning her on.
So what do you do when you see them?
Jump all over them?
Point them out?