Painting is such an easy and fun part of the display base construction. My advice is two keep the materials cheap. Craft paint from the local craft store is perfectly fine for what you're doing as well as cheap spray paint. I started by painting on any of the exposed foam portions with black paint. Spray paint has a tendency to "melt" foam so I don't want to take any chances.
Once that had the chance to dry, I brought the base outside for spray painting. I first went with a cheap flat black primer and hit the base. For the trim, I decided to go with a high gloss lacquer. This will hold up better to handling and creates some contrast (similar to the black rim of a miniature base). I hit that from multiple angles to make sure it coated within the decorative trim.
Everything I painted at this point onward was done with a 1" brush. When dry brushing it's best to go with a circular motion. This will blend better. Also it's even better if it's not uniform; go darker in some places, lighter in others. In the end I'll be using static grass and snow patches so that will help break things up as well. I first started with a pewter colored grey. I brushed this on to all the rock and cobblestones.
I then went with a medium brown (similar to calthan brown). A heavy dry brush was applied to all dirt areas and I even stippled some on to the cobblestone and blended into portions of the rock. I didn't wash my brush between colors so it helps blend some of the colors together. I think it makes things a bit more natural.
My next dry brush stage was a color similar to graveyard earth. I drybrushd across the dirt, heavier in certain patches.
I then started adding white mixed in with the pewter color and dry brushed it across all of the stone as well as a few patches in the dirt.
My next color for the dirt was similar to a kommando khaki. This went across the dirt and patches of the stone. I must have forgotten to take a picture of just this stage, but next I went with an almost pure white in patches. These are the areas that will have more of the snow mixture and again it breaks up the dirt texture.
Now comes the tricky part. For the river itself I want to paint the base of it and blend it into the rock color. I did a mixture of black and dark green and blended it up into the base of the rock. I then proceeded to work some of the pewter grey back into the base and went back and dry brushed in some grey/white. I guess this stage is a bit like the cooking shows where they wing it and add a bit of seasoning or wine to taste.
Once it dried I started with my first pour of water effects. Be sure to go with thin coats. Unfortunately this is an extremely long dry time; at least 24 hours between coats. Make sure that you give yourself adequate time before you need to use the base, this is not something to be done the night before the tournament!
I'll probably go with three coats of water effects done every two days. Here's my finished product so far. I'll wait until the very end before I add the static grass and snow.
It's an absolutely beautiful day outside today, so while my wife is shopping I'm going to bring my pallet outside and work on some painting on the deck. I'll work on the statues and barricades. I'm going to do some research on statues. If my memory serves me correct, Dave Taylor did some great looking statues for his greatsword unit. I'll look to his recipe.