Eh, negging is crap. I studied the PUA stuff yrs ago, most is jibberish. Negging is sold as a way basically for less attractive males to take a more attractive woman down a peg and supposedly level the playing field. If you're a somewhat attractive male, lift weights, etc have any personality or charm at all, you dont have to do that crap.
Now I will say, showering an attractive woman with compliments right off the bat is a losing strategy. She hears that shit all day between work, bars, online social media etc. so just fawning all over her is not gonna make you stand out in any way. But negging is a different thing. Just treat her like a normal person.
One strategy I did employ with a lot of success was "Cocky/funny". Its basically being sorta cocky but in a humorous and self-deprecating manner.