Most people now a days use negs incorrectly, they use the lines without knowing the purpose in using it and often throw out negs in quick succession to the point of killing a set.
Now, this is the main reason that I brought this up. Most afcs that are new to the community treat every girl the same. This is not the right way to go about it. If a girl is stunningly beautiful and stuck up use a fair portion of joking negs, but if shes an HB 7 with a innocent polite vibe you should rarely neg her, if at all. And the reason a pua negs a target is to show a target that you are not impressed with her. So give off that vibe (at least until she starts giving you IOIs).
Negs are meant to knock down a womens b1tch shields or ego. It can also be used to indirectly dhv by indicating your comfort around hot woman, meaning you most always be around them.
On a side note, I feel that push/pull and neg theory are often mixed up. Push/pull is more of a playful joke about the HB followed by a compliment(this is to give a girl mixed signals and to bate her into chasing you) and a neg is an insult about the girl thats so subtle that it doesnt piss her off but at the same time demonstrates lack of care on your part(this can show value while simultaneously knocking down hers).
Hope this was coherent.