There isn't really anything senders or systems can do, only a subscriber can move your emails from the Promotions tab to the Primary tab.
Studies show however that it isn't necessarily a disadvantage that emails land in the Promotions tab. It can improve deliverability, increase open rates, and decrease spam complaints. One should also remember that not all gmail subscribers have the tabs enabled.
You can just encourage your subscribers that they add your sender email address to their google contacts and/or ask them to move your campaigns from the Promotions tab to the Primary, in case it landed in the Promotions. Gmail asks if it should always deliver your emails there.