Clothing You don't need any special kit to begin with. Track suit bottoms are fine. Similarly a long-sleeved top is also a good idea. If you intend to run then wear lightweight things so that you don't get too hot. If overprinted maps are not being used a pen is essential to copy the course onto the map.
Most people use a red biro or a waterproof fine-point fibretip pen.
A compass is not required for the easy courses, but bring one if you have one. You could trip in the woods and injure yourself, so a whistle is advised, as a safety measure to attract attention. If it is raining, you will need protection for your map and control card. An A4 size clear plastic bag will do. Safety pins are also useful.