It would not be appropriate to teach without invitation, nor in a situation where the teachings cannot be reflected upon adequately. This is a significant point, as the Buddha's teachings are meant to be a vehicle, which one should contemplate silently and then apply. The value of Dhamma is greatly reduced if it is just received as chit-chat or speculations for debate. Accordingly, for a Dhamma talk, it is good to set up a room where the teachings can be listened to with respect being shown to the speaker. In terms of etiquette, graceful convention rather than rule, this means affording the speaker a seat which is higher than his audience, not pointing one's feet at the speaker, not lying down on the floor during the talk, and not interrupting the speaker.
Questions are welcome at the end of the talk.
Also, as a sign of respect, when inviting a monk it is usual for the person making the invitation to also make the travel arrangements, directly or indirectly. Minor Matters of Etiquette Vinaya also extends into the realm of convention and custom. Such observances, which it mentions, are not 'rules' but skilful means of manifesting beautiful behaviour. In monasteries, there is some emphasis on such matters as a means of establishing harmony, order and pleasant relationships within a community. Lay people may be interested in applying such conventions for their own development of sensitivity, but it should not be considered as something that is necessarily expected of them.