Appropriate level of formality
If people are of equal status, it is easier to become informal and call each other by first names. A junior person, however, should adopt the level of formality dictated by the senior person, e.g. if the MD of the company calls you (the junior) Mr Jones, you will know to call him Mr Smith; if the MD of the company addresses you (the junior), John, you will still call him Mr Smith unless he invites you to use his first name.
Understanding the hierarchy of a company will help you make the most of the communication and decision-making processes. To bypass a level of seniority in order to get a decision passed is unacceptable behaviour.
If you want to make an impression, a firm handshake is an important gesture of communication for any person, male or female.