The most important thing a person can do to make the most of meeting someone for the first time is smile. It is amazing the doors such a simple act will open. A smile can be the best icebreaker in the world, and knowing which smile to employ in which situation is one of the cornerstones to successful interaction.

In a situation where I am surrounded by people who I must impress because they are potential employers, or mentors, future parents-in-law, I find two types of smiles imminently helpful.

1. The shy smile. This smile is about half the size of a full smile and is presented with the head slightly lowered and the eyes looking up at the person. It is a smile that is non-threatening, yet allows the person at whom it is directed to recognize that you are open to interaction. Be careful, think really friendly thoughts while you are using this smile or you will just look nervous. This is not a Mona Lisa smile; you are not mysterious and secretive. You are open and eager to talk to those around you, but are waiting for them to approach you out of deference to their higher social position.
Note: Before you go trying this smile at your next office party, try it at home in front of a mirror. Look to movie characters you find friendly and approachable such as Julia Roberts (Another great shy smile a la Julia) or Anthony Edwards (Take two), for inspiration.

2. The outgoing higher achiever smile. This smile is a full on grin and should be accompanied with relaxed shoulders and a firm handshake. This is also known as a sell yourself smile. You are smiling with the intent of transmitting confidence, success, capability, intelligence and most importantly, Friendliness. Do not think things akin to “I am the shit” or anything else that will transmit a feeling of superiority. As above, you are still approaching those who are in a position of power over you. Here you are simply making the first step, instead of encouraging them to approach you. Therefore the attitude you are trying to express in this smile is not one of equality but one of similarity. This smile is supposed to tell those it is directed at that you are confident in this situation and are capable of being confident in others as well. Again, practice makes natural so please try this in front of a mirror until you are comfortable with it. Harrison Ford and Aiden Quinn both have great comfortable outgoing smiles as do Drew Barrymore , Lauren Graham and Alexis Bledel.

These smiles also work very well in romantic situations. The key to producing an icebreaking smile is to think about the impression you want to make, form that impression into descriptive words, and then send those words to their intended target with your smile. Practice these methods before you attempt them in real world situations but soon you will be on your way to engaging complete strangers with nothing but a grin.