Cat Stretch (or Cat Pose) and Cow Pose are great postures to warm up your back gently. They can be used toward the beginning of a practice, before moving progressively toward deeper postures. Try using them together, along with the movement of the breath.
Most of us have done these two poses at some point in our life. But a few great tips will help you gain more benefits out of them.
As you practice Cow Pose, focus on lengthening the spine. Try not to let the vertebras compress on each other.
Start with Cow Pose, on an inhale:
If practicing this posture by itself, start the same way as in the first two steps described in Cow Pose above.
Push down on the ground with your hands as if you wanted to get away from it. This will help you lengthen the whole spine.