Firstly, props for making out with that girl - I'm sure everyone on here has that one girl who 'friendzoned' them and you might be just about to break out of it!
The thing to remember with routines is that they are just ideas that have come from basic principles.
Work out what these basic rules are, and what suits your personality - and thats how you get natural.
For me, I made a couple simple changes - I'm a bit of a funny guy and one thing I stopped doing was making fun of myself, and infact, flipped it. Better to joke about how amazing you are, than how shit you are (following from this comes natural negging-back and forth). I also manned-up and brought more kino into my game and that made a massive difference.
I also stopped being such a cynical miserable bastard and started viewing everything in a more positive light - which made me a more positive person to be around (if you've read the game, the bit that sticks in my mind most is the bit with Tom Cruise and how positive he is).
So yeah, rather than following a script - word for word, set yourself rules 'Never: self-deprecate, Always: Make a joke at her expense' for example - whichever ones suit you and your personality. And when you do something wrong, think about it, and see if there is a universal rule you need to follow.
In particular with this girl - to not be AFC, just play it cool - don't 'can we talk about what happened the other night' or anything like that, just make out like its no big deal and carry on gaming her - you're probably gonna come across new sticking points at every stage with this one

but its all learning! we all have sticking points