The most overworked muscle is the Front Deltoid (presses); bringing out this aspect of the Deltoid does not add to your width, it only makes you look thicker!
How do you develop the lateral head of the Deltoid? Lateral Raises.
However Lateral Raises improperly performed develops Front Deltoid. the proper way to bring out the Side Strand is to start the Lateral Raise touching dumbbells in front of the thighs with all four bells touching; elbows slightly bent and raise to the side, keeping the weights in front of the body all the way up to ear level (no higher).
Now for the most important part of the movement: The Front Bell must be lower than the Rear Bell. If the Front Bell is higher you are working the overworked Front Deltoid again. Remember, all bench presses and dumbbells work with the dumbbells held with palms facing the lower body are 90 degree Front Deltoid.
Another aspect of Laterals is to round your shoulders forward and also use your elbows as a concentration point. In other words, lead with your elbows – and last, but not least – keep your knees slightly bent during the exercise. And always work in front of a mirror to catch any flaws in your performance.
(IronMan Magazine Jan 1977 Vol. 36 No. 2)