it worked a few times for me. you sit the girl down so she's comfortable, and while your dick is still soft and kinda floppy. just sort of squat over and "dip?" it down till you feel her throat. then just slowly push more and more down. let her suck, but dont try and move out because you wont be able to fit it down again when you start getting hard.
haha, i know it sounds stupid, but it worked for me, and it feels great when you do it right.
only thing is just make sure you take it slow, cause they might freak out and start gasping for air, or you might hurt her if you start getting too greedy. she should be fine as long as you sit her so she can breathe well and let her hold your hand.