I think a key principle is *don't make it into a disability when it doesn't have to be*, and from what I see, you've been doing a pretty good job in that area. When you're not sure what the accepted behavior is in a situation, though, that's a pretty good guide. Basically, a disability in this context is something that removes a person's power to accomplish a goal, such as "talking without awkwardness", "communicating effectively without interruption", or "successfully engaging in an activity with a friend". Those things might be hindered for her if her stuttering is treated in a certain way. For example, as others have said, don't complete sentences for her, which falls into the above rule because doing that takes away from her power to communicate with you, since the control over what she's saying is being hijacked. The same thing goes for eye contact - sometimes breaking eye contact can imply an awkwardness that doesn't have to be there. Another good example that might not be obvious is making a big deal out of her stuttering. If you make it a big thing in your conversations with her, it can feel awkward talking about anything, because of that lingering feeling that the topic will always shift back to being about stuttering. It's a prime example of unnecessarily making it into a disability, and yet it's probably the most common conscious decision people make when interacting with a stutterer (as opposed to an unconscious one, like averting eye contact, or even finishing words for some people).