Tips to properly do a lateral raise:
The hardest-working muscle during the lateral raise: your middle deltoid.
Stand as tall as you can.
Set your feet shoulder-width apart.
Your arms should be straight out to your sides, so that they form a T with your body.
Keep your core braced.
There are several variation to this exercise:
Alternation lateral raise with static hold
Stand holding a pair of dumbbells straight out from your sides, as you would in the “up” position of lateral raise.
Lower and raise one arm, then lower and raise the other. That’s one repetition.
Bent-arm lateral raise and external rotation
Grab a pair of dumbbells and hold them at arm’s length with your palms turned toward each other.
Bend your elbows 90 degrees.
Without changing the bend in your elbows, raise your upper arms out to the sides until they’re parallel to the floor.
Rotate your upper arms up and back so that your forearms are pointing toward the ceiling.
Pause, then reverse the movement and return to the starting position.