For a start, it may be a good idea to climb a hill, and get a good look around.
Maps are good if you know where you are on the map :idea:
In the northern hemisphere, there is a star that is almost exactly in the north at all times, the Polaris or Northern star. It is pretty easy to find, if you know the "Big Dipper". Take the two stars at the end of the "Big Dipper", and make an imaginary line "upwards", and extend it five times the distance between the two stars that is Polaris the northen star. That way is always north. :idea:
If you have an analog wrist watch, you can use the time to find north. Hold your watch up in front of you, and let the short hand, that indicates hours point at the sun. While holding it like this, cut the angle between the red arrow and 12 o'clock in two, (noonwards if the time is before 6am or after 6pm), that way is south. (The reason you need to cut it in two, is because the clock takes two rotations while the sun takes one around the earth, it is of course the other way around, but never mind.)
If you have a digital watch... your screwed. :lol:
As far as trees go it is little sketchy.... First of all, there will be fewer branches to the north. This is usually easiest to see if you look up along the trunk of the tree. The north face of the tree would be more humid than the south face, which is something most species of lichen (or moss) likes, and consequently, there will be more of it on the north face.
I wouldn't rely on trees to point my way home :!: