I once read a book about deciduous wood land that estimated how many tons of leaves fall. So if I was going to get a sense of that I had to keep on adding leaves, and to get the variation in colour that occurs. The leaf of gold that children try to catch soon changes colour once it starts to rot down.
I also had to add in the scantlings and fallen timber. I started to dapple the tree trunks and added a bit of moss in at their bases.