Send Your Own Signals
Acknowledge what the woman has said by "mirroring," or saying a slight repetition of a key word in her statement. For instance, follow a remark about wanting to go out, with another remark saying, "So, you'd like to go out?"
Smile in response to what has been said. A true, open smile that reaches the eyes and crinkles the cheeks is warm and inviting. It will also brighten the eyes and convey that you're open and receptive to further flirtation.
Use your body language to show that you're open to the girl's advances. Stand with relaxed, uncrossed arms, turned towards her and give a soft touch, if appropriate. You may also move closer within her personal space, but leave at least a foot of cushion for comfort.
If a woman flirts by touching you, stay relaxed and at ease. Cover her hand with yours if she's touching your arm or hand. Don't move quickly or jerk away, because that conveys discomfort and insecurity.
Openly acknowledge the flirting with some light, inoffensive teasing that calls attention to it. Make her laugh, and she'll open the door to even more interaction.
Remember, absence makes the heart grow fonder. Flirt for a bit, but be ready to move on for a while to whet her appetite. In a club or bar, be certain to come back after an appropriate interval to buy a drink or dance; don't act like the lady is out of sight and mind.
Brushing Her Off
Avoid smiling or laughing at the flirtatious remarks. Keep a level, even voice and still face. Give the idea that the woman's words have no effect on you whatsoever.
Make your body language distant by keeping a lot of space between you and the woman in question. Keep your torso turned outward, and don't make direct eye contact. Cross your arms in front of your chest or cross your legs away from the woman.
Make monosyllabic replies, or simply nod. This will close the door to further conversation immediately.
Don't stick around. Otherwise, signals become confusing and vague. Leave within several seconds of the unwanted flirting in order to break contact decisively.