Like with other types of photography, be candid, respectful, and anticipate events to come. If you’re at a birthday party, there will be gift openings, candle blowing, etc… See these events coming and plan your shots well to document the event. Do your research and ask where and when appropriate to photograph. If you are documenting a wedding, approach the officiant before the event and ask for permission.
Try to use natural light when applicable, but remember to soften harsh high noon sun by seeking shadows, or using shading techniques. Add light to bring out detail in shadows and to avoid washing out the detail in bright spots. Use shutter priority for longer exposures to highlight the subject and blur the background.
Compose using the rule of thirds, remember background, lighting, depth, and subject all play a key. Subject is the emotional center of the photo, so once found, use as many compositional tools as you can to highlight and draw in the viewer.