Light colors “advance” a home while dark colors cause it to “recede”. This means that lighter shades will make your home appear larger and closer to the street, while darker shades make your home seem smaller and further away. If you want your house to blend in and be less noticeable, therefore, a darker hue is best. Light dramatically affects how colors appear to the human eye. In cooler climates the light is diffused and bold colors are intensified. In southern climates, the harsher, brighter sunlight will cause pale tints to appear washed out.
If you want your gutters and downspouts to be less noticeable, paint them the same color as the house.
Make sure any mildew problems are solved before painting. Test suspicious spots with household bleach and if they change color, you definitely have a mildew problem. Moisture problems must be eliminated before painting. If they are not, water will ruin even the best paint job.