Understanding how to navigate without a GPS and having the maps to do it will be a huge benefit to any group in a grid down situation. So it got me thinking that you may also benefit from the knowledge and will need to take advantage of it while it is readily available.
Here is an explanation of how to use an eight digit grid and plot it on the map.
Here are some good tips when you are out in the field:
Before you plot, verify you have the correct scale on the protractor and you have the right side up. Don't laugh, I had to correct Soldiers doing this very thing. A little information can be dangerous.
You can find several excellent Sergeant produced power point presentations online with a simple google search. The Art of Manliness offers this quick rundown to using a military map, protractor, and compass. If you have any questions, let me know and I will answer them to the best of my ability at this remove. Plotting your point correctly is half the battle and getting the correct distance and pacing is the other. Plot twice and take your time and you will be half way there.
Most of us do not have the benefit of a ready pool of experience when it come to this kind of skill set, so I would recommend another quick Google search for orienteering groups in your area. Oh, and if you want a challenge, try your hand at urban land navigation. And what if you really get good, and you feel the need to separate the men from the boys? Go do it at night.