Everybody knows first impressions really do matter. But not everybody knows that the "first impression" is formed just in 7 seconds when we meet somebody. 
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When we see a person for the first time, we automatically scan the face expression, check the hands and the neckline, and finally examine the shoes. These focal points help us in a preliminary analysis of a stranger. Remember the last time you attended a public event, say a conference, where you met a new colleague or a potential client:
I bet you looked at his/her face, probably memorized a friendly smile or some extravagant expression; 
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you checked the hands, and I don’t exclude you noticed some particular gadget, a wedding ring or a shiny Rolex, which gave you an additional couple of clues about your vis-à-vis; 
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then your eyes moved to the neckline, and you saw a badge with a correct spelling of the name, the rank and the company of this fellow. 
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After some seconds you dropped your eyes because your grandma taught you not to stare at people, and voilà you inevitably checked the fellow’s shoes. 
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So this is the way it works. But that’s not the end of the story, because we tend to look for imperfections. People constantly judge other people. Prejudice and bias can seriously affect our communication, so it is vital that we mind our manners and uphold our dignity.
To make a good first impression, try to focus on your vis-à-vis. Make direct eye contact and switch your active listening mode on: in this way you will remember the name of the person in front of you, ask smart questions and make him/her feel in the center of your attention.
We trust more to self-confident people, and we endeavor to appear as such. A firm handshake is the first step to communicating self-confidence. Always use your right hand to greet people. Remember this rule and keep your smartphone, papers or a glass of champagne in the left hand at public gatherings.
A vertically parallel position of your palm shows mutual respect and equality. 
Avoid displaying your palm downwards or upwards, it communicates superiority and domination.
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Pump the hand two or three times and let it go. If you are not a president posing at a photocall, stand up when you are offered a handshake. Don’t shake hands across the table, go around and respect social distances. /Firm-handshake-GettyImages-521811101-58db29763df78c5162605f22.jpg)
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And last but not least: SMILE! 
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I hope you take into consideration these basics, do your homework on your focal points before you go to a public gathering, and make good and lasting first impressions.