--10g dedicated line with quality outlets. (Unfortunately some codes require crap safety outlets so you may need to swap these after inspection)
--if using led lighting, place on a separate line. Carefully consider lighting options. Ceiling cans are nice for task lighting but I do not like them for when I listen to music. Have some nice accent lighting options.
--carefully research room dimensions and where you anticipate speaker and listening chair placement. Can be hard to predict but clearly some dimensions will have fewer standing wave problems than others.
--do you want windows? I opted out as they are not nice acoustically and I wanted to achieve acoustic symmetry as best I could.
--suggest double dry wall with a layer of "green glue" adhesive
--Crown molding in acoustically your friend.
--Use a solid, heavy door to the room and a seal on the bottom is suggested as well.