Using a comfortable set of Dumbbells

While keeping a neutral spine, slightly bend the knee and hip with most of your weight on the heels of your feet

Bend at the hips in a 90-degree position where the dumbbell are fairly close to the floor for full range of motion.

Slowly lift the dumbbells in laterally  away from the body to shoulder level

As you are coming upward, angle your thumbs downward to feel more of a contraction slightly pause for 2 seconds at the top 

With each fly rotate your elbow away from your body for complete shoulder activation

As you hit shoulder level gradually come down slowly and repeat.