@Neox It's not a basemesh. I'll try introducing some triangle, but sparingly! =) @okidoki That actually worked well! The shading artifact is now much reduced and there's one less pole so the topology looks much cleaner. Thank you @"Eric Chadwick" I'll check it out. Thanks
I think you could be working on features in isolation, rather than holistically. And this makes things much more difficult. Similar to trying to sculpt in high-res without refining low, and increasing gradually. I would suggest starting with a low mesh, and complete all the loops, before adding complexity.