Lateral Raises

Lateral raises work the middle delts (lateral delts). This is an area that isn't trained much by the compound exercises.

How to do a lateral raise.

• Stand a dumbbell in each hand by your sides. 
• Keep your back straight and brace your core
• With a slight bend in your elbow, slowly lift the weights out to the side until your arms are parallel with the floor. Don't rush the reps, keep it slow and controlled.
• Hold it in the top position for two seconds before lowering it slowly back to your sides.

Common mistakes

Having your arms completely straight
Having your arms completely straight puts a lot of pressure on your shoulders. Have a small bend in the elbows and keep them like that for the whole rep.

Dropping their elbows
It's common for people to drop their elbows as they lift it, so their hands are much higher than their elbows.  The upper arms don't go through much of a range of motion when you do this. I like to cue people to lead with their elbows to ensure a full range of motion is achieved. 

Using momentum and swinging the dumbbells
There is very little resistance at the bottom of the exercise, so it's very easy to generate a lot of momentum at the start and swing it up.  This takes away from the muscle working at the top part of the rep where there is more resistance. 
Do all the reps in a slow and controlled manner with a pause at the top. Don't rush the reps.

Letting your arms move forward
Keep your arm out to the side. Letting it come forward at all it'll take the work away from the middle delts.

Shrugging the weight up
Shrugging the weights up moves the work towards the traps instead of the middle delts.