The bulk of the grunt work is now done, so time to step back and assess. Most likely the first thing you'll notice is that the entire map is quite dark. The best way to lighten it up is adding an adjustment layer as the top layer in your stack (Layer->New Adjustment Layer); which type you choose is up to you: Brightness/Contrast is easiest, Levels allows a little more control, and Curves boasts most control but can be tricky.
You could also play with the color scheme in this same way by adding an adjustment layer for Color Balance. Even the Photo Filter can offer some interesting, subtle color effects.
Also, if colors look a bit too neon/pastel for your tastes, add an adjustment layer for hue/saturation.
This is really just the "play" stage, so try a few things to near your vision for your map.
Below is the before & after version of my map, showing the adjusted colors and brlightening.