1) Pick out outfits that compliment each other.
2) Rake up piles of leaves for a fall background scenery.
3) If you want to pose them, pick poses that are comfortable.
4) Let your children play, and capture the moments.
5) Snap lots of pictures, so you have more choices when editing.
6) Edit to add those final touches.
7) Most of all have fun and enjoy each other.
Here is a very easy to use photo editor that I just adore.