Repetition, I work on the phone and was petrified at first, but making 100's of calls a week I got used to it and got better, now calls don't bother me at all, I suppose I've become desensitised by doing it so often. I still have hiccups but deal with them like any other. I think once you get over 'the phone' it becomes much easier. I also know therapists say not to change words but I managed to figure out what I can and can't start a call with, through experimentation. Sorry I haven't given any actual tips, but that's how I overcame it.