So I've been experimenting with negging. I feel like that along with my change in attitude and approach has been giving me positive results. Not all of which are apparent to me but I feel it.

I've noticed it does not work on everyone. What I've been doing is practicing on several people. A lot of which do not range between 8-10 but below. This is all of course practice, which will not result in too much backlash.

However, I negged a friend, who is engaged (again for practice), about how she has a cute overbite like Bugs Bunny. A neg I got from Neil Strauss' The Game. She "liked" the post on FB as well as a friend of hers. On Snapchat I mentioned it again and she came back with me saying, "I feel self-conscious about that." I feel as if I did this to anyone who was a 7 or below, maybe even an 8, they would take it in the same fashion. At least if done twice. Once I feel might create the desire for them to DHV in some way. For example, if I tried it on my ex, of whom I am friend with, it might not work because of our history. She might take it as an insult. This of course does depend a lot on the "package" or way it is given. Doing it without a "haha," "lol," or smile might be taken as an insult. But I feel even with those things just mentioned it might be received negatively.

Any advice or guidance is greatly appreciated.

Negging is an integral part of a successful game and to my experience it seems that nonverbal negs outperform verbal ones.
Your bugs bunny one seems a little insulting because it decreases the appearance of a girl to a rather ridiculous one.
Even you wouldn't like to hear something like this.
A girl wants to express femininity and not cartooninity...

All I can tell you is that I don't like negs that involve her body or her features. Its shit that she can't change and you run the chance of hitting on something that this girl is SUPER anxious about and fucking everything up.

So when I neg, I do it in terms of how she's acting or I'll tease her about how she's overdressed or under dressed for something. I'll tease her for being too girly for me, or not girly enough for me. Depending on what's happened.

I know it's super old school but I still love mystery's old line about "is she always like this?" or "I can't take you anywhere". Of course it's all said light hearted with a big grin.