Judgements on likeability, trustworthiness, and attractiveness can happen fast—perhaps as fast as one-tenth of a second according to a 2006 Princeton University study. Basically, the brain likes to stereotype, and it is hard to argue with it. Carolyn Gregoire discusses the factors to maximize good first impressions in an article for The Huffington Post. Being well-dressed and having a firm handshake do play into it, but things that are more challenging to control, like tone and tenor of voice, also elicit judgement calls. If you have any choice in the matter, make a first impression in person, as even first impressions made over video statistically turn out more negative apparently regardless of other factors. One more important thing to remember is that between trustworthiness and confidence, broadcast the former first and the latter second. Confidence is important, but if you all ever do is take charge of the room, nobody will like you enough to view that as a good thing.
You can view the full article here: http://www.huffingtonpost.com/2014/05/30/the-science-and-art-of-fi_n_5399004.html