I'm trying something different with Luna. Yesterday the plumber (who is obviously a dog lover) was over and, of course, all Luna wanted to do is bark in his face. Instead of telling her "no" and getting her to back off, I tried bringing Luna near him and giving treats and having her do tricks to make her associate visitors with treats. I'm not sure it made a difference...it definitely quiets her down
in the moment and keeps us in a better mood, but that's it. If I stopped she went right back to barking and growling in his face with her hackles raised, especially if he paid any attention to her or carried something large. The plumber was like, "she knows she gets treats for barking!"

Should I continue with this method and see if there is an improvement or try something different? By now barking at people (including people she knows and plays with) is a habit for Luna.