So the challenge with working into dry paint, is not only matching colors, but getting a smooth transition between the wet and dry layers. this is compounded by the fact that colors dry slightly darker, so even if things look perfect one day, it may likely look not so perfect the next. As I mentioned in the 'Portrait of Sarah Explainer" post, this is where mediums come in most handy for me. I use Oleogel pretty sparingly while I'm painting, mostly just to stretch certain paints that might be a little harder to work with. but when working into dry paint, I give the area i'm about to work adjacent to a very light coat of Oleogel, just to bring the colors back and to create a more accepting surface. that way as wet layers overlap onto the dry layers, they don't sit so much on top of the paint, but visually blend more easily into it. I'll frequently work quite a bit on top of the dry layers, then use a clean dry brush to "fade" the new stuff. that way, if my colors end up being a little off once things are dry, there isn't a hard line in between the two sessions and it's much harder to notice.
This mess is what my pallet looked like a few hours into the second or third session on this piece. Essentially my habit is to throw some warms down; some combination of yellows, cad orange, cad red, and my trans oxide brown -- then cool down and purposefully muddy that mixture with purple, blues, greens, and maybe a little black. I didn't do a great job documenting what colors I used where with this piece, but I'll try and write more about my palette and color mixing in the future.
This (above) is probably 4 separate days of painting, maybe 10-11 hours total. unlike the last piece, I didn't have any areas that needed super obvious correction at this point, where the transitions between two separate sessions stood out. I think that's likely because I did a better job painting those transitions, and I painted this one slightly looser. the freckles actually helped here.