I like throat fucking, I usually lets girls know this is what I am looking for.
It's best to ease your way in, let the girl to deep troat, balls deep. Get her used to it and hold it at the bottom of your shaft, try that 2-3 times. Then the next time she is ball deep, start thrusting her throat, a few times of doing that and she will be slobbering and even tearing all over your cock.
Most girls will do it in longer session and thy get warmed up.
There is a mix of not being able to breathe and the gag reflex that leads to a good gagging session. But the girl needs to feel in control, so don't push, just work your way in