To start with I simply drew a rough line to mark the coast and the island. Then I laid down a thin wash of blue for the sea and light green for the land. Once dry I applied extra washes of; grey for the mountain, darker green for the forests, ochre for the swamps/marshes, and a slightly stronger blue for deeper areas of the sea. The rivers and mountain details were added in with a slightly thicker paint mix, and roads/settlements were added with rough dark pencil. At this stage the map was very powdery so to stop the colour rubbing off I sealed with a thin mix of water and PVA glue.
The A2 sheets are available from the Squarehex site here:
http://squarehex.myshopify.com/collections/square-hex-pads/products/a2-20mm-numbered-hex-sheet-tube-of-10-sheets