Here is a rough draft of the map created for the book with the finished graphically rendered version above it. Visualization is the only way that I know of writing out scenes: picturing the setting, the characters and then trying to capture the moment in words. It is also helpful to visualize the dialogue and their body language to see if it makes sense. I'm sure other people have insights into how they like to write, but I wouldn't get through the first chapter without it.
When researching the Campbells in Scotland, I used old maps of Ayrshire and battle maps from the first Jacobite Rebellion to figure out how to approach various scenes. Old maps and paintings of Portsmouth NH were also a great reference to layout routes for the antagonists as they made their way to the frontier. The old cliche about a picture being worth 1000 words is multiplied by another 1000 when it's the only insight you have into historical settings.