To begin a dumbbell row start by putting your hand on a bench or on your knee. Grip the dumbbell with the other hand. Your stance should be staggered. When you grip the dumbbell visualize your hand as a hook, and initiate the pull through your elbows and back. Keep your upper body at a 90 degree angle throughout the movement. Take a deep breath in and brace your core.
As you row the dumbbell off the ground keep your upper body straight and your elbow tucked to your side. Resist the urge to shrug your traps to help with the row.
Keeping your shoulder blades tight and squeezing your back as tight as you can, bring the dumbbell to your side.
As you lower the dumbbell, do so in a slow and controlled manner, letting the dumbbell come to a hang, in order to get a good stretch on the lats before starting the next rep.