Renew your lumber camps and build more mills

This may seem pretty obvious to some, and maybe you know to do it, but the amount of times a low to mid-elo player has not made additional lumber camps or mills is astounding in the late game. Perhaps too many things are happening to remember it.

Nevertheless, renewing lumbercamps and building more mills leads to less walking time for villagers, which increases efficiency of your resource collection. This small amount adds up!