A good defensive approach starts before you make contact. The goal is to approach on an angle so you can anticipate where the attacker is going instead of simply reacting to her movement.
If you approach an attacker square, she can beat you underneath or over the top. That puts you in a reactive position.
Instead, approach on an angle.
This allows you to understand where the attacker is going and meet her at the right spot. From there, you can either trap her with a double team or force her to roll back.