Taking pictures of people is a bit different than taking pictures of inanimate objects because if you don't photograph at the right angle or with the right light, somebody's going to be unhappy with the way they look. Keep a realistic expectation in mind, and don't make promises you can't keep. While you may want pictures that look a certain way, you might not have the skills to deliver the results. Of course, the more you practice the better you'll get.
Don't try to take pictures at a straight angle. Sometimes, the best pictures are those where the people sit or kneel and you stand above them. Let your subjects smile naturally. When they are together and they relax, then their natural reactions will shine through, giving a beautiful image instead of one that looks forced.
As a people photographer, try to keep everything as simple as possible. You don't always need the most extravagant backdrops or props. Sometimes, the best pictures are taken using natural lighting and the things that are already in the background instead of adding a lot of extra details. Try to find an area that is flat if you're taking pictures outside so that the surrounding details can come into play when you take pictures. Perhaps the biggest thing is to be aware of those surrounding details. You don't want to take the perfect picture where everyone is actually looking at the camera with a nice smile on their face - and then find out there's a tree growing out of Aunt Mary's head.
When you take pictures of people, you're going to need to play around with a few of the settings on your camera. These settings will allow you to zoom in and out along with giving you a margin of error while taking the pictures. Some of the settings on your camera can allow you a bit more freedom when editing pictures at a later time before delivering them. Try to find a camera that has multiple settings that are needed for taking pictures of not only people but inanimate objects as well. Take the time to learn about some of those settings and what they do before you get the family together for that important photo.
Also, have fun and take plenty of pictures. Even the ones that aren't perfect will bring back memories in the future.
