Years ago, I visited Wendy Palmer Sensei's dojo, just north of San Francisco. I paired up with a woman who turned out to be at about the same level as me. For some reason which I still don't understand, we connected at a deep level really fast.
Our training became rather intense with the both of us trying to reverse the other as much as possible. A number of times we ended on the ground grappling. Wendy came over apparently concerned, but seeing us laughing, walked away.
My point is that this training was very helpful to me, but was only possible due to the positive mood we had and the fact that we were about the same level. The rules of the dojo, made by O'Sensei, state that one must train with a feeling of joy. It was this feeling that allowed us to train at a high level and be able to finish that practice feeling better than when it started.
I believe the first step in training is to establish a good relationship with my partner. Without that, it is immpossible to advance, even on a technical level.