Increase the learning curve. After major negotiations, spend time as a team making enhancements. For more minor situations, review on your own or with a colleague or friend. See your team members as coaches. The purpose is to continually learn and get better.
Negotiation provides a wonderful opportunity.
Because you negotiate all the time, you have lots of real-time data to reflect upon to continually improve. But improvement doesn't happen automatically. It requires discipline, a team culture and individual mindsets for doing so. Enhance the comfort level within the team. The more relaxed a team is the better it will perform.