One other thing: don't use patterns on the hull. The only patterning type I used for BC models where of two type: grids or a pattern I did for mechanical parts (before I started doing them by hand - a lot better and cleaner looking that way).
Instead, any paint program that has layers makes your life easy as hell with doing aztecs. If you really want to, add the overlay patterns to the specular map, not the diffuse, it will look a lot better and more believable that way ;) And don't make Federation ships specular maps grayscale, that fits late Romulans the best, and to an extent the Klingons, but use colors (from opaque shades to the ones that really stand out, depending on what you want to accomplish). Add to that what Wiley said about subtlety.