Ya I think traditional art experience does inform the process quite a bit when it comes to form and light and stuff.
Even though it's traced the goal isn't to represent what's there completely but more of a gestural simplification, the simpler you can get while still capturing the essence of the thing, the quicker and more confident you'll be in choices.
Look at images of a low quality and literally do the most basic ass shapes to try cover the space and see how simple you can get while capturing the gist, then you'll start seeing those shapes in images everywhere and always be analysing how to break them down to varying degrees of complexity while still capturing their essence.
For hair and eyebrows and the like try go full tilt at lots of examples of ultra high res images so you get a sort of muscle memory of what physically exists in the space in terms of its construction like flow of strands, direction of growth etc THEN look at very low res images of hair and eyebrows and see what grand gestural shapes within them stick out the most, then apply the skills from learning the hi-res with the basic nature of the low res shapes and you can eventually apply that to anything.
Eventually you start to get a sort of innate sense of what SHOULD be in places so you can sort of mindlessly invent shapes even if they arent actually there to capture what it is you want
For these pics in the thread ranges between 10min >>416632
and 30 min >>416543
depending on how much effort I'm in the mood to spend.
Hopefully this helps or even makes sense