Now, there are a few common misconceptions regarding your GRIN to be addressed:
1. Your GRIN is happy. Maybe it is! But most likely, it isn't. When you see a chimpanzee GRIN, you should probably stay away because you are about to have your face torn off. A GRIN is different from a smile because it shows how many teeth we have, and teeth are our best natural weapons. Don't believe me? Try chewing a carrot with your hands. You'll probably find that you cannot.
2. Your GRIN is natural. Many people think you either have a GRIN or you do not. Surely a GRIN is limited by the size of the mouth and the teeth it contains, but that is beside the point. It is what you can convey with a GRIN that is important. Think of it like a blade. A gleaming perfectly sharp set of teeth shows you what they can do, but a worn and discolored set shows you what they already have done. Both of these closely relate to misconception number 3, which is...
3. Your GRIN is in your mouth. While it is true that the displayed portion of the GRIN is toothy, the most important aspect of it lay in your eyes. It is said that the eyes are the window to the soul, and the importance of the GRIN is to convey that you have none. They should remain fixed and staring while you bare your brightest facsimile of the thing called a smile that your stupid fucking teachers told you was a good thing.
So now that you know some mistakes all make about GRINS, what can you do to make the most of yours?
Well, the most important aspect is practice. Your GRIN is a muscle, and like any muscle it can be developed to a natural and harmful state. But muscles have limits where GRINS do not. If you overdo it using a muscle, it will strain, whereas if you overdo it using a GRIN, those around you will strain. Indeed, just as a blown muscle will never be the same again, neither will your interpersonal relationships.
Your GRIN is deceptive. While those who GRIN and other savvy masters of body language understand that it's an anxiety reflex of cornered and dangerous animals, pretty much everyone else mistakes it for a smile, which they see as weakness. These are the best sorts of people. Not only do they misunderstand your intentions, but it is generally indicative of a wider lack of true comprehension of the world around them! This is the perfect opportunity to teach them that teeth are not nice things.
Treating your GRIN is as much physical as it is psychological. It is fine to say one should encourage one's GRIN in confrontations, but that is only half the battle. Be sure to brush and floss regularly, drink plenty of water, and gnaw upon the cast off bones that your weak ass dog fancies itself too good for.
For further references on the subject, remember your case studies. Roger, of course, whose GRIN is a Harbinger of Reality and surely a sign that you have not been paying attention to the Way Things Are. Alty, whose Alaskan-forged GRIN by necessity creates the two categories of Those Who Have Seen It and Those Who Still Have Their Noses. Nigel, whose GRIN says to you Yes You Should You Should Always And Forever Just Once More There We Go Do It Again Hahaha Yes Once More No Never Mind All That Pay It No Heed You Should Hahaha Why Are You Screaming.