When you first engage in a conversation with another human, it's important to greet with a smile. If you go from your default idle face to a smile, your subject suddenly feels a lot less intimidated by you and the likelyhood of a hostile interaction is greatly reduced. When people have their defences down, in this sense, they are more likely to take orders from you and are less likely to impede your progress. After your initial smile, don't hold the dumb grin on your face. Holding a smile let's everyone around you know that you feel awkward and nervous and the smile loses its potency.
Greasing the Gears
In situations where you might be asking an individual to go beyond his requirement of self-preservation, it's necessary to confuse them somewhat in order to increase the likelihood of them agreeing with your request. To do this, first look at your target in the eye. This initial look is intimidating and, to an extent, flusters the mind and prevents proper focus. The next step is to, without breaking eye contact, flash those pearly whites. This gives your confused subject a comforting feeling and a general good impression of what you're saying. Not only is your subject partially impaired from thinking about your statement in a fully rational and critical sense but, thanks to your sparkly grin, he's also given a positive emotion about the conversation before he can fully understand it. When used properly, there's no limit to what the smile-gaze combo will get you.
Arming yourself the Teeth
Keeping your smile potent is extremely important if you want to yield maximum results. There are some basic guidelines to maintaining an effective and appealing smile.
Always have a chapstick on hand - You'd be surprised how often you use a chapstick when it's on hand. Cracky, bleeding lips won't charm a donkey
Use a good toothpaste - Toothpaste is something you definitely don't want to be penny pinching. The difference between a crappy toothpaste and a good quality one is a couple of bucks but the difference is astronomical. Look around for the shiniest, most futuristic looking package. That one with the little whitening strips in the paste is just tits. Leave an extra tube of toothpaste and toothbrush in the shower. If you're doing something that requires fresh smelling arm pits, it's guaranteed to also require fresh breath.
Floss Picks - Starchy foods tend to get stuck in your molars and between your teeth. In case you weren't aware, decomposing food has a nasty habit of smelling like shit. Having some of those floss/pick hybrids in the car will help you pick some of the smile-comprimising fecal matter out from between your teeth when you have a free moment.
Should you find yourself in a hostile encounter, a smile can be the difference between a pleasant pat on the back or a boot up the arse. When a hostile situation is in the making, beguiling the sad fancy into smiles and pointing out the absurdities of the situation will, most likely stop a guy from needing to show off his manly skills and throw you a 1,2 knockout. I'll write about body language for avoiding the fight, but for now we're discussing the smile only. The most important part of this smile is actually your eyes. The difference between a face smile and a real smile is that, in a real smile, the muscles around you eyes (orbicularis oculi) contract. This is what squints your eyes. Why do you need to know this? Eye gaze is a very intimidating and palpable thing. Squinting your eyes to reduce this reduces the intimidation factor and decreases the odds of the first punch being thrown your way. In return, it also hides your eyes from signalling when and were you will be punching, should you decide to do so.