Here is my method, for what it's worth. First I boil new traps with a little dish soap, unsented if possible to remove the machine oil. Then I rinse and reboil in sagebrush tips. This will darken the traps a little and put a faint sage smell to them. I only land trap and my traps are buried so I don't worry about the darkness of them. After they are dry I will dip in melted canning wax or parafin (sp). This will help protect them from the salt I use as antifreeze at the set and will act as a lubricant and make them faster. Make sure the wax is hot, but not smoking and it will make a more uniform coat that will stick to the trap. I like to do this step outside as the wax can be flamible if it gets too hot. After waxing them I will pack them in a plastic tote with some sagebrush to give them a little more sage smell.
I use sage because it is the predominate plant in this area. I would think that in Nevada you would have about the same thing. If not you should be able to use what-ever is native around there. I've heard of using cedar, grease wood and other natural vegitation that is local.