Even though your feet remain on the ground, it should appear that you are dangling by your arms. They must remain extended as you grasp the wall.
Push into the wall with your legs. Your body should be parallel to the wall at first, and this would seem to be pushing you away. However, your arms are holding your close, so all momentum that pushed you away from the wall will also force you up. Just as you are beginning to develop momentum with your leg push, begin to pull with your upper body.
