You can also make an improvised compass in a way that allows the apparatus to be more portable and less vulnerable to the wind. Tie a thin bit of cotton thread to the eye in the center of the razor blade, and hang the blade inside a jar or bottle where the wind will not reach it. Make sure it is hanging freely, and it will line up north-south.
Marking The North End Of The Needle**
You'll have to use something like the sun, moon, stars, geography, etc. to find north, south, east, and west. Once you have that, mark your compass needle with a pen, pencil, marker, or a scratch to show which side is pointing to the north.