What type of clipper do I need to clip my golden retriever?

I need to keep my Golden Retriever clipped down due to skin issues in our our very hot / humid environment in SW Florida - Per Our Vet. She has very thick, curly fur which grows back very quickly and we can't afford to have this done every month, but I'm not sure what type of clipper I should get or the proper length of blade. We do need to take her coat down Very short for air circulation. Can anyone help me with this? I tried googling it, but there were so many conflicting posts. Do I use a guard? Any help would be appreciated!