A forest in a dream usually represents the unknown -- parts of your mind or your life you haven't mapped out yet. Wandering among the trees without a clear path can mirror a real situation where you're unsure which way to go, while finding a clearing often signals that some clarity is starting to emerge from the uncertainty.
The Fixed Stars do imitate the nature and action of the Erraticals or Planets, whereof they transfer their actions unto them. - William Lilly (1602.-1681.)