Thanks a lot, wish I could claim some sort of secret, but truth is, it’s “donkey work”. Trying something, seeing how the uv map looks, setting edge seams, try again. The big issue with the mask bit was the sticky-out bits which weren’t on the edge. The key thing I try to hold to is the “unfolded paper” idea, so look for areas that can make sense as a “surface”. Also, as tempting as it is, sometimes, it’s better not to “make quads” on a UV island as it affects how the final texture looks. With this, I found, looking in the UV window, there were clear places adding seams made sense. Until recently, I tried to all seam marking in the 3d viewport, but really, I’d say the UV window was even more important when refining.