First off... Welcome Aboard!
Have some 'rep' for showing us a map in your first post *bonk*.
What font to use is really a matter of choice - though if the lands have let's say have a asian 'flavor' to them maybe you choose a font that has a similar flavor.
You can add a pattern overlay to your ocean (assuming it's on its own layer) or find a nice seamless water texture instead of using the solid color.