The point of blurring part of the photograph while keeping another part in focus is used to emphasize something in the picture. So first you will need to pick something worth emphasizing. This is extremely easy to do with wedding photos. The bouquet or especially the wedding rings are a beautiful focal point and easy to make the dominant part of the photograph.
Try to find different focal points, often times with infants their own fingers and toes make great focal points. Couples are a great place to experiment with fingers, since holding hangs is considered a sign of affection, focusing in on there can help define a photograph as loving.
Have your subject interact with the focal point if it is an object. A child holding their favorite toy towards you, usually says more than photographing that same focal point on the ground a little ways away.
The key is experimentation, try new things and new photo angles. Try out new focal points, you will be surprised to find that you may like some of the photos without your subjects faces in focus better than ones with them in focus.