That's a tough one because there is no right or wrong way to do it.
It really depends on the space you are filling and what feels good to you. Here is a link on how to hang groups that includes links within the article to further explain "how to". One great tip: use wax paper to trace your layout once you've made a decision. Then tape that wax paper to the wall and you will have a guide to put your nails. It makes it much easier to hang and you don't end up with a lot of nail holes. Good luck.

http://tipnut.com/hanging-pictures/

Thank you. I think I finally got it the way I want it by moving the grouping to a longer wall and expanding horizontally. The wax paper idea is tremendous! Thank you so much!!!