TIP #9: Use a Triangle as a Composition Technique

Triangles are an underused tool of composition, and yet it is probably the most important rule of composition for shooting group photos.  It will be unlikely that you could successfully shoot a group photo following the rule of thirds.  Wouldn’t it look strange to have the family squished off into the corner of the photo and then a giant space of nothingness in the rest of the shot?  Yes, it would.

So the best way to compose group photos is to use triangles to your advantage.  Have the group positioned so the bottom of the people is wider and have only one person at the top of the pose.  This makes the group look like a single unit and the composition looks complete.

Source: Improve Photography