It depends on the place, time, situation, who the person is and if it's in a group or private setting.
Doing it unprovoked just makes you look like a douche and is not really effective.
I find it best to do it when she insults you first. Nothing beats the potency of a well timed unexpected comeback.
Weight is usually one of the biggest insecurities of most women.
Age is another big one. The older a woman gets, the less attention she starts to get. This can be very unsettling for those who are used to so much attention during their younger years. It's no surprise that the anti aging cosmetics industry is a multi billion dollar industry.
Sometimes, simply ignoring a woman and acting like she doesn't exist works to great effects. Women thrive on attention. Especially male attention. When they don't get it, they feel inadequate. They start to wonder if you don't find them attractive. Without even saying or doing anything, her insecurities start to come up in her mind. "Maybe he thinks I'm fat" or "He probably finds Christina more attractive".
Honestly, I find ignoring and pretending they don't exist to work best. Just go about your business. That way you don't have to worry about how to neg them. Only neg when provoked.
