great post but I would add that your GPS unit will give you a grid north reading and if you have a compass you need to know your declination for the area you are in. You need to set your declination or correct for it. In some areas it does not make that much of a difference between true-grid-magnetic, however the farther east or west of the central meridian of your zone if you are using state plane coordinates, or the farther north or south you are from the equator you are going to get a fairly large declination. (for instance where I am at in western washington it is 22 degrees. and a guy can get pretty turned around heading on a bearing that is off by 22 degrees) also you need to be aware of what side of the prime meridian you are at. if you are on the east side you declination correction will be northwest whereas if you are on the west side you correction will be northeast. Just something to keep in mind if you use a handheld compass in juncuntion with a gps.
If you get a compass get a good quality one like a silva that you can set your declination on
Last edited by heavywalker; 09/17/09. Reason: compass recomendation
