These are informal affairs. I would suggest you read about business practice and organizations if you wish to have a bit of insight. I found it useful when I learned there is little tollerance for distance between levels in an organization. That is to say, authority power isn't respected, but by all means respect competence and charismatic leadership. If you come from a country such as France, where the distance is large in comparison, you may make your prospective employer feel uncomfortable if you come dressed in a formal suit and show a high level of respect. Instead, focus on professional skills, the content of who you are and not the packaging.
