Doing tonal underpainting is something I've taken to doing of late in both trad and digital media. I'm not entirely sold on it but it's got definite benefits when it comes to making things stand out, and it also means you can put off worrying about the colour scheme, and can make changes without needing to match colours, which is a particular benefit in traditional painting. It also enables shapes and volumes to start taking over from lines, although I am still a line person at heart. I would rather look at a detailed architectural drawing of a, say, Rouen Cathedral, than a fuzzy impressionist painting of it. I think there are three default artistic mindsets when it comes to image making:
1.medieval- most interested in outline,
2. classical- most interested in form and volume,
and 3. Turneresque/impressionist- most interested in atmospherics.
I am conventionally line orientated, but am coming around slowly to the other things.
On a fairly unrelated note, I've had the benefit of a critique of a piece by the good people at Ninja Mountain. The piece was 'Retours', which evidently contained some faults that I failed to pick-up upon (or about which I entered into a state of denial) at the time. One lesson of importance was to establish perspective at the offset, otherwise the only solution is to introduce a lot of shadow to hide mistakes. I've also got to try to vary facial expressions more. I've got in the habit of painting fairly bland expressions. Sometimes, however, the subject calls for a bit more warlike of a look.
Here's some additional encouragement, from Gilbert and Sullivan:
His nose should pant
and his lip should curl,
His cheeks should flame
and his brow should furl,
His bosom should heave
and his heart should glow,
And his fist be ever ready
for a knock-down blow.
And from Shakespeare:
In peace there’s nothing so becomes a man
As modest stillness and humility,
But when the blast of war blows in our ears,
Then imitate the action of the tiger:
Stiffen the sinews, summon up the blood,
Disguise fair nature with hard-favored rage,
Then lend the eye a terrible aspect...
set the teeth and stretch the nostril wide,
Hold hard the breath and bend up every spirit
To his full height...
Here is 'Retours' before and after the critique. (Normally I wouldn't tinker with a commissioned work after it was approved, but in this instance it required it, and the original client has been given the option of using the revised version, for which time should still allow).