The compass is an invaluable tool for navigating in the mountains. Before getting to grips with how best to use it, it is important to understand all the features of a suitable compass for hill walking and mountaineering.
The base plate should be large enough that you can comfortably grip it in your hand. The base plate will have on it a direction of travel arrow that should always point the way you want to go. In the picture it is the small black arrow just above the magnifying lens. Also the base plate should have romer scales for at least 1:25000 and 1:50000 map scales that allow you to easily measure distances and take grid references. These are in the top right hand corner of the base plate in the picture. Other features of the base plate can include a magnifying lens, small hole for accurately marking your map through and rulers in cm and mm.
The compass housing (or bezel) contains the bearing dial showing degrees in 2 degree inclinents, the orienting lines which include a red arrow that points to north on the compass (these can be lined up with the grid lines on a map that run from south to north) and the red needle that points to magnetic north. An index line on the bearing dial that lines up with the direction of travel arrow is where a bearing would be read from.
A lanyard is usually attached to the compass. I have mine tied into a pocket on my rucksack waistbelt or to the zip pull on a jacket pocket to save losing the compass. If you are going to wear it around your neck, the lanyard must be long enough so you can comfortably hold the compass out in front of you whilst walking on a bearing.