Does anybody here know the process to becoming a certified NRA firearms instructor? I'd definitely be interested in becoming one and would want to work with rifles mostly. My hands shake too damn much to be to good with pistols lol.

NRA Training Counselors (there are several of us on the island) can offer classes for Basic Instructor.  You apply to take the class; if accepted, you take the class, get your credentials, and proceed from there.  LIFE offers Basic Instructor classes every year or so, usually focusing on handgun, but we have offered rifle and shotgun as well. 

Not to discourage your desire for personal growth, but there's not a lot of demand for rifle or shotgun instructors here.  Since there is no training requirement for the purchase of longarms, most people don't take basic classes. 

You may find that you'll either need to approach a Training Counselor directly or travel to the mainland to get a rifle or shotgun class.  I don't think I've ever seen one advertised here, and the ones LIFE has run have either been for a partnering organization (like Boy Scouts) or for existing LIFE instructors wishing to further their credentials.

I think there could be a good market for a rifle instructor program if you market it right.  There are a lot of rifle/shotgun shooters that just buy a firearm and don't know what the fundamentals are.