Difficult Conversations, Douglas Stone, Bruce Patton, and Sheela Heen
A secular title geared toward guiding you through difficult conversations in both professional and personal settings. The book is divided into sections on sorting out facts and each party's responsibility, discussing each party's feelings, and identifying ways each party's sense of identity is on the line in the situation.
Encouragement, Larry Crabb and Dan Allender
Encouragement is more than saying nice things - it's connecting with others in a way that builds everyone up. The basic premise of this book is that our relationships suffer from lack of an outward focus because we're all afraid our needs won't be met. As we learn to trust God to meet our deeper needs, we will be more available in our relationships.
How to Win Friends and Influence People, Dale Carnegie
The motivations/tone are definitely worldly, but the suggestions are what we teach all the time: listen, ask good questions, try to take a genuine interest in other people's lives. This is a good book for anyone, but it is especially helpful for people who are just learning how to build social skills because it is so practical.
Loving God's Way, Gary DeLashmutt
Reclaiming Friendship, Ajith Fernando
The Relationship Cure, John Gottman
This is a secular book with very practical advice about the influence of small interactions and what Gottman calls "bids" for connection on our relationships.
Speaking the Truth in Love, David Powlison
Spiritual Relationships that Last, Gary DeLashmutt, Dennis McCallum