To gain control and reduce jitters during the interview, it is always better to prepare beforehand. Thorough research into the company and the profile you are applying for to determine how this career path is a good fit for you. Scour everything you can find about the company and learn about the various ways you can be a part of its mission.
Ensure arriving on time on the day of the interview to leave a good first impression. Consider planning out the outfit a night before to have it ready the next day. Aiming to arrive early will not only allow you to sit quietly and collect your thoughts but also allows you to stay calm and stand out from other employees for all the right reasons.
The general tone of the interview should certainly be calm, polite and friendly to establish the critically important element of rapport. Brushing up on general communication skills & showing up in formals can also further help showcase your skills effectively. Try using non-verbal communication skills as well like making eye contact, smiling and nodding.