A Fall Theme Wedding is a very romantic theme to choose.
Fall trees are very pretty to have at a wedding ceremony and/or reception.
The wedding dresses in the photos above are some good examples of what would work good with this theme.
You could have orange, copper, gold, brown bridesmaid dresses.
Fall cakes with orange, red leaves, and desgins on them...
...Flower girl dresses that match the color that you have chosen to use.
The place cards could be fall leaves that you could DIY.