Contact the Arizona Film Commission. They have the most resources in the state, and it is their job to provide access to the best locations Arizona has to offer. This is usually the first call all professional location scouts make.
Contact the local chambers of commerce in cities that have possible locations where you would like to film. Some of the most popular locations are Phoenix, Flagstaff, Sedona and Monument Valley.
Contact Arizona tourist agencies. They will have detailed information about the most popular tourist locations and the cycles of the tourism season.
Watch films shot on location in Arizona. During the end credits, read the names of the location managers or location scouts. Make a list of them to contact.
Call or email the location managers or location scouts of a film shot on location in Arizona. Ask them for any contacts in the state. Location managers and scouts are great about sharing information and resources.