The key to mule deer hunting in Idaho is of course field glassing. Success or failure will greatly depend on how proficient you are at looking long distances and being able to resolve what you are looking at.
There is no magic potion or set of instructions to help teach glassing. It basically just take many hundreds of hours with your eyes glued to your binoculars or spotting scope and learning what mule deer look like at great distances. The only thing I can really tell you is you’re going to have to learn how to be meticulous. For most people glassing for hours on end seems monotonous, but let me reassure you that there is no substitution for success.