Bent-over lateral raise
Emphasis: posterior deltoids and middle trapezius
Sit and bend forward at your hips so your chest is as close to your thighs as is comfortable. Hold dumbbells under your legs with your palms facing each other and your elbows slightly bent. Keep your head in a neutral position by looking at a spot on the floor that's about 6 inches in front of you. Lift the weights out to your sides to shoulder level while keeping that slight bend in your elbows. Lower slowly and repeat.
Tip: For maximum contraction in your posterior delts, focus on using only that muscle to move the weights. If you don't concentrate on using your posterior delts to move the resistance, your powerful mid-back muscles will come into play, reducing the effectiveness of this exercise.
Dumbbell lateral raise
Emphasis: middle deltoids
Stand with your feet shoulder-width apart, knees slightly bent. Hold dumbbells in front of your thighs with your palms facing each other and your elbows slightly bent. Lift the weights up and out to your sides to shoulder level while keeping that slight bend in your elbows. Lower slowly and repeat.
Tip: For maximum contraction, your wrists, elbows and shoulders should be level at the top of the movement.
Overhead dumbbell press
Emphasis: anterior and middle deltoids
Sit on the end of a bench or chair, with your back supported if possible, holding dumbbells at ear level with your palms facing forward. Push the weights overhead by straightening your arms, but keep your elbows soft - don't lock them in the finish position. Return to the start position slowly and repeat.
Tip: You shouldn't bang the weights together at the top of the movement; you should just touch them lightly. This will ensure that you always have maximum control over the dumbbells and maximum tension on your muscles.