Using a softened start-up; making statements that start with "I"

According to research by Dr. John Gottman, the way that a conversation starts is often the way that it will end.  Therefore, if we can phrase our complaints by stating our feelings and our needs, rather than attacking the other person, we are helping our partner to know how they can support us.  We are less likely to seem critical when our statements start with "I" instead of "you."  We can say something like "When... I feel... I need..." 

This article from the Gottman Institute talks about how to soften our start-up for more productive conflict management.