Start sitting one facing the other side by side and have your partner push you in some way (remember to include the face and neck in this drill) as he pushes catch his entire body with the contact and your eyes and move yourself so he pushes in one way and you go along with him on your own volition and push him somewhere else so his body is spread and open to work with.
An example will make things more clear: your partner is pushing you with the hand closer to you in your shoulder backwards. You move your body back so he gets no support from your body contact and add a rotation of your hips so you roll away from him. Your leg rises with the hip turn and either pushes his non working shoulder back or works on his head and turns his look away from you and as you roll to the side you can control both your movements. Remember to stay within and avoid locks which lock you as well and open you to attacks and also lock your eyes and attention on him rather than the whole and remember to also work with him starting the push/pull at your back and at various speeds so you learn to relax and lessen the initial shock of contact (strong push or shove) and work.
Simple is not always easy 🙂