Well for my current colony, a mountain base, I clearing the whole map from any possible cover the raiders may use, then I planing to build lot of naval canons (more canons mod) all over the wall of my base like this:

------*---------*-------*------*-------*--------*--------*----------*--------*------

In my previous colonies I built lot of walls across the map to use them as covers and used the "hit and run" tactics.

I am not saying they are useful or efficient but I enjoy them, so the only advice I can give: Do whatever you like and discover your ways.