Frankly, at the beginning? Anything you feel like. You can start, perhaps, with Just a title of what you're doing, pomodoros style.
Maybe a note of something you thought but couldn't follow up on that moment.
Diagrams are good. Much easier to think and much better and faster doing by hand. I always get distracted by the tool when I'm drawing in a computer. Even artist-modd
I also make bullet points of general ideas that I'm trying to accomplish.
Doodles.
Important thing is, don't fret. Over time you'll find how it works for you.
And I'll add that it in practice it is not even that much unless you're doing some serious training, like a professional athlete. For most tasks, the accurate depth perception from this fades around the length of the arms.
The archaeologists know that and say as much in TFA:
"The paints used in the reconstructions are chemically similar to the trace pigments found on parts of the surface of the originals. However, those pigments formed the underlayer of a finished work to which they bear a very conjectural relationship. Imagine a modern historian trying to reconstruct the Mona Lisa on the basis of a few residual pigments here and there on a largely featureless canvas.
How confident could we be that the result accurately reproduces the original?
This point is not actually disputed by supporters of the reconstructions. For example, Cecilie Brøns, who leads a project on ancient polychromy at the Ny Carlsberg Glyptotek in Copenhagen, praises the reconstructions but notes that ‘reconstructions can be difficult to explain to the public – that these are not exact copies, that we can never know exactly how they looked’."
I noticed that pages about countries are good hubs for this kind of connection. The page cites someone, their page has a link to his country of origin and these country pages are really extensive and have links to a variety of topics.
Moving the head/body goes a little further, but that was not my point.