Generally, all traps need to be cleaned of their factory oils. A few common ways to do this is to rinse them off with a pressure washer, taking them to the car wash, or putting them in a dishwasher.
The next step would be to let the trap sit out in the yard to begin the rusting process. If you would like to hurry this process along you can soak the traps overnight in a bucket of water and vinegar or salt water.
After the traps have rusted you will want to dip or dye the traps. If you are a water trapper you may want to use a dip as it gives a bit harder protective coat and will decrease the time it takes for the traps to rust again. Land trappers mostly use a dye because it is mixed with water instead of gas therefore there is less smell on the traps.
Most trappers choose to wax their traps because it protects the traps from the moisture that causes traps to rust and it also provides a lubricant that will let the trap fire faster. Body grip traps should not be waxed because it makes the traps hard to handle and there is a better chance it could go off when trying to set it.