There is a question about the title for a ruler (What royal title can an absolutistic ruler have?). That is a question about the title for the ruler and it was very well answered.
But: How to speak with them? (Or rather How to start speaking to them?)
For example, related to my world, queen Iris is a very benevolent ruler and so she allows if people speak with her in a somewhat familiar style.
Miss Iris, could you ...
It is obvious that this style is more suitable for speaking with (for example) teachers than rulers (and she was a teacher before she was elected to be queen - and she did not give up that job. Weeks have 13 days and so she has much time to do both).
What words might be better suited for speaking with rulers?