Research the Company
Most hopefuls when going in for an interview barely know the company they are willing to work for. That is a big mistake indeed. Whoever is going to be interviewing knows you will only be impressed by one way and that is if you actually show interest in the company he is working for and by doing a little a research before going in will greatly improve your chances of winning his grace.
Confidence is probably one of the most important aspects of anyone going into an interview. There is not a single company out there that is looking for someone nervous and not prepared. Being confident about who you are and your capabilities is what will make you different from all the other professionals looking to grab that post. HR managers are not looking for those who want to waste time, but instead, are there to get what the company is looking for.
Dress for the Job
One of the biggest mistakes people make when going in for an interview is either under dressing or over dressing. You should always dress accordingly to the position and that does not mean, in any case, that your clothes should be messy and untidy. Wear clean, pressed and proper clothes and if you know that the company is not against casual dressing, do not hesitate to mix things up a little.
Not bringing a resume or any other necessary documents is just a real turn off for whoever is interviewing you and it certainly deems you as unprofessional and unwilling to really work hard for the company even if the company may not have directed you to bring one. Coming as a person who is ready to start from day one is what all hiring managers are looking for and not making that impression just takes you way down a long list of potential candidates.