It is great when you can just not worry about what the other person is thinking! A habit I have that really helps me just for small interactions where you don't really have time or it would be odd to say you have a stutter(just like ordering food or something like that) is I just have a really well rehearsed and upbeat "hi how are you?" I know I can confidently say it. But the trick is to wait for them to actually respond to the question. People in customer service are so used to be treated as servants and not like people, when they feel like you are actually acknowledging them as a person they are almost always more positive towards you and for me it dissipates alot of tension out of the situation so I stutter less and I worry less if I do stutter. I guess it is just treating people with respect and you'll get respect back but it definitely helps me from a stuttering point of view.