After seeing my portrait images my lot of friends & visitors asks me about my used equipments & where that shot was taken? I found most of them are having keen interest to know which was the lens I have used. But I guess sometimes they miss important thing about the expression of the subject. In portrait photography that is most important. Did you take care your subject is comfortable or not? It's not a major concern when you are shooting your family members but not is the case while shooting strangers.
People photography requires a special skill & it comes with practice. I know whenever two strangers meet it's difficult to crack the bottleneck of not being comfortable with each other unless you have some work. I have found most of the people (at least in India) are eager to be get photographed. As I have written in the description of my many images on Flickr I try to have conversation with them. I take their early shot knowing that they are not my best one & try to have communication with them. I try to realize them that they have no harm from me, my shooting & I am not at all less than a friend. Winning the confidence of the subject is a key. After only that you will get nice expressions from them.
In children photography also it is very important to be patient & giving the kids there time to talk. Kids are impatient & it's your turn to understand them, balance the situation by being patient. Giving breaks in shooting helps them to relax. Experimenting with them adds their interest in the shooting. Giving some gifts like toffees & chocolates also helps. You have to talk with them as if you are a kid, that greatly makes them comfortable & more are the chance to get nice shots. Keeping the camera to the eye level of your subject really makes them comfortable as well as viewers of the image
In family portraits while shooting with 2-3 people you have to arrange them to portrait the relation,emotion along with affection. You have to comfy them for getting close enough to get nice compositions.
Hope you like these tips & will take care in your next shoot out.