Cord is all about texture
So let that take center stage and choose a color that's classic but not put-you-to-bed boring. Go for hunter green, rich marine blue, teddy bear brown or sunset yellow. The classic sports coat deserves an equally classic hue.
Unlike leather, cord does not look better with age. Retire anything with too-worn cuffs, or get messed-up elbows updated with a suede patch. If it's too far gone (and you should know when that happens), pick up a crisp new blazer with an updated fit.
Cord comes in varying degrees of thick or thin wale (this refers to the ribs of the fabric). You should go for thin to medium. Thick-wale corduroy slides too quickly into leisure-suit territory.
Resist the urge to get too comfy in your cords. The jacket should fit sharply, if it doesn't fit that way off the rack, take it to a tailor.