In order to take accurate readings, it is essential to have a good quality compass. They can be purchased in stores that sell sporting goods or outdoor equipment. They can also be ordered on-line through the internet. If at all possible, you might try to find a few friends who have compasses and experiment with them before making a decision as to what features you desire most in a compass and which ones you can live without. These things usually become apparent right away.
Some compasses are more sensitive than others.
This made it nearly impossible to use for recording angles. It also reacted to the rocks on which the drawing board was placed. These may have had some metalurgical property to them. The needle of this particular compass would spin wildly in the presence of metallic objects. When you look for a compass, you might try placing several objects near the compass like a pen or a key.