Relationships also come in all sizes and colors - there are romantic relationships, work relationships, and friendships, just to name a few.
Regardless of what kind of relationship you want to strengthen, each is fundamentally similar to the next in a number of ways.
In all healthy relationships, we are able to listen well, empathize, connect, resolve conflict, and respect others.
The following TED Talks are a great refresher course in doing all that.