Made progress so seems like a good time to put in the steps so far to get to where I am with Andalla. If anyone has any tips or comments I'm always happy to get feedback especially if they help make things easier on me or look better in the end.
STEP 1: I started with my zoomed out map of the Archipelego as shown in the original post. So I transferred the major settlements and features from that to the new, more zoomed in scale maintaining the measured distances (going from the, admittedly weird, scale of 1:13,300,000 to 1:2,500,000) and drew in the rough coastline based on the original design:
STEP 2: Next step was to wobble that coast line to add in that detail some more and add in the major river courses and some islands. Still working completely in pencil (using a 2H lead) I've darkened the line in the photos so that it's easier to see but I keep it pretty light at this stage.
STEP 3: Partially through additional coastline and river detail (notice that this time I'm darkening the line somewhat. Still fairly light and enhanced in the photo but more definite than previous pencilling). I've also started sketching in the mountain range:
STEP 4: More mountains and starting to ink. The coastline/mountain ink is De Atramentis Document Ink - Brown. The black ink is a Pigma Micron 0.001. I deliberately use a light water-soluble blue ink for the rivers (Staedtler fine-liner) because I want it to dissolve into the watercolour and basically disappear but I like to have it inked initially so that I have something to guide me and I can erase the pencil that would otherwise show through the transparent watercolour:
STEP 5: This is where I was at when I first posted my in-progress (now updated with my latest progress)
I forgot to get a photo at full inked stage unfortunately but because this post is already long enough I'll start a new one with the start of the watercolouring