The coastline and the territory borders are nicely drawn. But you're going to need the bonus area names here. Maybe put them inside those coloured squares.
As for the colours, they are a bit.. ugh. Hurts the eyes, so bright... All red & orange & pink, just... try to drop the saturation of the colours a bit. Or choose some different ones. Just because it's a southern america country doesn't mean the colours need to be all bright and warm.
As for graphical advice... some drop shadows on the playable areas maybe.
Since you're using paint.net, I
strongly advise installing at least these plugins if you haven't already:
http://paintdotnet.forumer.com/viewtopi ... 16&t=22819 <--- shaped bevel, outline, vertical/horizontal flip
http://paintdotnet.forumer.com/viewtopi ... 16&t=22881 <--- drop shadow