Make sure the compass is flat when using it:
Your compass must be flat to detect the magnetic north correctly. For example, place your compass in the palm of your hand. When using a map, place the compass on the map on a flat surface.
What if your compass loses its bearings?
Use your compass away from magnetic sources or it could lose its bearings: high-voltage power lines, mobile phones, keys, metal objects, etc. Even another compass might affect the direction!