So you're creating that beautiful board, and you've made the fill territories semi-translucent, looks great. Test fill your territories and your Navy comes out as Grey, or your black looks brown, not to mention trying to tell your default 'brown' (which is really just a rusty maroon) from your rest.

Just found this great tool.
http://www.colortools.net/color_combination.html 

Step 1: turn your fill transparency all the way down. 

Step 2: Screen grab your board image and paste into your favorite image manipulator (ex: paint.net)

Step 3: use the color dropper to find the hex value

Step 4: go to above site, enter obtained hex value into Color 1, Choose a Color 2 and combine.

Viola! This will give you the result you're going to see.

I'm playing with it to find what do i mix with Color 1 to get the Navy that I want. wish there was a color wheel to pick the 2nd color to make it a bit easier to find it quickly. but meh. i'll find it.