To find my way—
In a world which—
I’m a muttly stray—
Is a miraculous thing.
The information which follows is from: The Natural Navigator, by Tristan Gooley
In the northern hemisphere, using deductive reasoning, if the sun and moon both appear to move in an east-west plane, then it follows that when it is not a new moon and the sun and moon are not together, the moon must be roughly east or west of the sun. This means that the light side will point to the sun, which will appear roughly east or west of the moon. The bright side of the moon is acting as an approximate compass, pointing west or east. However, reading a compass in the sky is not very practical, so the best thing to do is to extend a tangent to the crescent line that separates light from dark down to the horizon. This line will be perpendicular to the direction of the sun and any line perpendicular to an east-west line is a north-south line; this line will touch the horizon reasonably close to south if viewed from northern latitude. This method tends to work best when the moon is high in the sky.