Configuring a device's "children" entities on new, blank dashboard

I see it’s easy to hide the entities I don’t want to show, but need help on how to put only the entities I want in a new dashboard. I’ve been reading the docs & playing around with the dashboard editor, and I suspect I’m missing is the relationship between dashboard, cards, domains and devices. From what I gather, domains are either a class of device or a class of entity.

All device entities are grouped together by default, so adding a device to an area add’s all of it’s entities too, which results in a very cluttered area view. There are too many (51) entities per device, and I would like to put them in different (I believe) cards so I have more fine grained control over their placement. Perhaps labels could help, I don’t know. I’m not comprehending the available structures and their hierarchy / relationships. The only thing I see that’s easy to observe is areas seem to be at the top of the hierarchy.

I need a way to treat a device’s entities separately for a more flexible arrangement on the dashboard is possible. I see plenty of examples of dashboards that appear to have cards with individual entities. I recall someone mentioned that for my energy monitor devices templates could be used, but I don’t see how they fit. Perhaps if I can get one device’s entities put where I want them templates could ease the configuration of other devices of the same type. That would make sense for a template.