I offer coaching in a variety of ways depending on your goals and experience, and have no preference for actually using Arena specifically. I find reviewing logs on 17lands.com to be particularly efficient, but could also use Magic Online, Arena, or just talking over a decklist or spreadsheet. Consider this "lesson" to be extremely flexible. Private sessions should generally be booked in the afternoon, and Streamed sessions at night.
This is the same as the private Magic session except it will happen on stream so that viewers can learn from it as well. Streamed sessions should generally be booked at night, and private sessions in the afternoon.