It's a fair enough question. What the gun world in general accepts as being 'an instructor' actually requires very little. Go to the NRA page, find an instructor who teaches the 'basic instructor' course, usually combined with the 'basic pistol instructor' course, take a weekend, spend a few hundred dollars, and congratulations, you're an instructor. This doesn't mean that you have the real world experience people like to see in an instructor, or that you have the charisma and insight and engaging personality people like to have in an instructor. (Particularly in this field, people are assured when they feel like their instructor is someone who has good odds of winning a fight.)
I am in the process of setting up an LLC, to instruct the state CCW course and also perform minor gun-related services, and I feel like I have accumulated enough of a resume to be respectable. I'm a veteran of two wars, I've been carrying since 1995, I have a degree in criminal justice, and I can demonstrate a detailed understanding of current law. (The other reason I had been wanting to get certified for a long time, for boy scout activities involving firearms, they now require that the instructor is NRA certified.) Despite all of this experience, I don't feel nearly as qualified or competent as the old cowboys and veterans I grew up with.