When choosing his "Houses" (family) colors/tinctures (as well as symbols-visit: http://www.fleurdelis.com/meanings.htm for meanings of some of the most common designs), a Lord would often use a common list of color meanings to make a statement about himself and his beliefs.
Common Color MeaningsMetal Gold (Or): Wisdom. Generosity, Faith, Glory
Metal Silver (Argent): Innocence, Peace, Purity, Sincerity, Truth
Black (Sable): Consistency, Grief, Prudence, Wisdom
Blue (Azure): Chastity, Faith, Loyalty, Strength, Truth
Green (Vert): Abundance, Hope, Joy, Loyalty in Love
Maroon (Sanquine): Fortitude, Patient in Battle, Victorious
Orange (Tawny/Tenne): Worthy Ambition
Purple (Purpure): Justice, Regal, Royal Majesty, Sovereignty, Temperance
Red (Gules): Magnanimity, Martyr, Military Strength, Warrior
Furs: were usually identified via black dots on a colored field and most often represented "Dignity." Ermine was one the most common fur design. A standard rule of tincture was metal must never be placed upon metal, nor colour upon colour, this is thought to have allowed a stronger contrast, making the shield design stand out clearer.
The significance each color could vary somewhat between countries and over time; but these are among the most common meanings.