The number one thing you can actually do with a collage is tell a story. This is what you''re trying to do. You have a lot of different directions you can go with the story. If we were to stick to wedding example, you could do it in a chronological order. The arrival of people, everyone waiting for the bride, etc. Or you can tell it differently. You can start with the wedding kiss that unites two families and start the stor y like that. It gives you a lot of different things you can do.
Another interesting thing about these collages is that you can add in other things besides pictures. You could put large font from the song playing during the first dance of the newly married. It is little things like this that create a real story that anyone can look at and see.