This article is from the Aerobics Fitness FAQ, by email@example.com (Robles) with numerous contributions by others.
Your body should remain in good alignment. This means your head is
up, shoulders down and back, chest up, abdominals in. When
stepping up, lean from your ankles and not your waist; this will
avoid placing excessive stress on the lumbar spine. Contact the
platform with your entire foot, rather than allowing your heel to
hang off the back; this will avoid stress and possible injury to
your achilles tendon. When stepping down, step close to the
platform and allow your heels to contact the floor to help absorb
the shock. (toe, ball, heel).
When doing lunges or repeater steps, the foot that stays on
the step should support your entire weight. The foot that
touches the ground should barely touch down, rather like you are
dipping your toe into cold water.
You should not use hand or leg weights when you are stepping, as the
risk of injury outweighs any added benefit you might get from using
weights. It is important to note that anyone with a history of knee
problems should consult a physician before beginning step training.