I know everyone here has helped out people like me with post openers and you are probably getting a little tired of it now but i could really use some help. I personally have no problem with openers, engaging a girl is easy. But time and time again i find the conversation drifting off into nothingness and i'm fed up with it. I'm unsure when to introduce negs when talking to a single girl also. So what is the best way to intrigue and attract women whilst moving on to the next step?

Seduction, but this is only how it works for you. Think of the times you had a girl laugh or really liked to be around you, and try to apply the same stuff on the new girls.
Most of the time it's just about small talk, get her number, and good bye. Most of the times you actually spend more time with a girl is when you naturally click, conversation is easy, there's a lot to talk about, you both share things in common, etc...
But, there are times where you get hints that the girl is interested, but you're screwing her up with boredom, this is where u shift your focus on her and only her, so ask a few questions about her and try to keep a conversation from her replies. Also, ask legit questions that interest you, not bullshit questions that don't interest you because these almost always end up in quick conversation-finishers.

And what about the negs? I really underestimated them at first but i have seen them in use, unintentionally admittedly, and the do really work. Again, no idea whats appropriate and when?