Typically, you will get most sunlight on the (northern hemisphere) south facing slope, or with the clearing to the south. A post from How To Find North Without a Compass tells us how to find north without a compass and with one. We can then know what is south most facing.
"Using a GPS:
I really like my Garmin Dakota 20. This like many GPSs tell you your location, direction of travel, distance traveled, elevation, barometric pressure (for storm watching), and can plot your traveling history, which can be used to get back to where you started. A lot of them have compasses on them. These are probably the most precise way to navigate, but come at the disadvantage of all electronics... batteries. Due to this, you should have many backups for navigation.
A lot of cell phones have them now and can be used as well, although, not quite as accurate as a field GPS.
Using a Compass:
A compass points to Magnetic North, not True North. And the degree of error between the compass and true North changes based on your location. One degree of error, could get you almost half a mile, or around 300 meters, off during navigation. Learning to use a map (which I want to do a video on) will be your biggest advantage when using a compass, because you can determine the direction of travel, based on "map north" and known visual markers. But if you know your angle of error, you can move the Bezel ring to mark True North on your compass. Look for my video to come soon on this."
Use Link: How To Find North Without a Compass