wouldn't it be contrived to not trace over the outlines directly on a new layer? Or is that somehow impure? Kinda struggle with this.
It depends on what you want to learn. The easiest way to copy reference in Photoshop is to select it, copy it (ctrl-C) and paste it (ctrl-V). Otherwise, if you are studying colours, anatomy, construction, proportions, line quality, whatever, you are better off treating your reference as reality, which cannot be traced, copied or colour picked.
Grinnikend door het leven...
Nevermind tracing, it should be immediatly obvious that you're not learning anything by doing that. What baffles me most is people copying (without tracing, but often with colour picking) the photo ref almost pixel by pixel until the "painting" looks exactly like the ref. There's lots of that on the FB group of conceptart. Why would you do that? Granted, there are a few people who're just having fun, enjoying the chorus of "woah, that looks just like a photo!" from the uninformed audience, but I'm sure some of them really think they're learning something other than copying pixels. Which they're not.
I think if you do use photo reference instead of drawing/painting from life (which most, myself included, don't do often enough anyway), you should always make the image your own. Design your painting. Stress some things, play others down. Cameras are really bad at some things. Subsurface scattering, skintones in general, subtle colour variations, extreme contrasts. Cameras suck at those things! Don't copy photography's flaws!
Even with reference it can be intimidating for a beginner to draw without something to hang on to. You can compromise though. What I usually do is just create a simple X and Y axis (or diagonals) through whatever I consider the main aspect(s) of a drawing. Those 2 lines can be the 'spine' or point of reference you can always return to, to build up the rest of the drawing.
"Work for your self first. You can paint best the things you like or the things you hate. You cannot paint well when indifferent.
Express a mental opinion about something you are sensitive to in life around you. There is a profound difference between sensitivity and sentimentality."
~ John Sloan Gist of Art
Don't compromise yourself. Creating axisses (ha, I just made a new word) is fine, as long as you don't draw these on your paper reference. You can create a viewfinder with axisses, or even a grid, and you should develop some system of construction lines, but don't cheat your way out...
Grinnikend door het leven...
It depends. If you're learning, it's pretty useless, tracing without knowledge still results in a bad drawing.
If you're using someone else's photos, you need to be careful because 1) it's someone else's photo, and 2) chances are someone will recognize it.
You need to know what you're doing so that you're tracing only information that's useful to the piece, and not mindlessly copying. You need to be able to make changes on the go.
Donato traces his photo reference (which he shoots himself) sometimes. Nothing to prove, he can draw like the best with or without them.
When I'm doing production work, all bets are off and I'll use every cheat and trick I can to meet the deadline.