adelgary: Having recently interviewed about two dozen people for a full-time position at my workplace, I've seen a lot of different attitudes and behaviors, men and women.
First off, always be confident. I know it's rhetoric, but just walk in there and sell yourself. Be positive. Be familiar with your skills/strengths/experiences. (One guy I interviewed, fresh out of college, couldn't come up with a reason when I asked him, "What do you think best qualifies you for this position?" I actually had to read him his resume to try and help him come up with an answer.)
MAKE EYE CONTACT WITH THE INTERVIEWER WHEN YOU'RE TALKING. I can't believe some of the people; they would look down (lack of confidence) or up (lieing) when answering me. A majority of the interview comes down to how you handle yourself. A candidate could be the most qualified, but if he/she can't be social and calm and comfortable and sell themselves in an interview, they're most likely not going to be hired.
Never be self-deprecating when talking about yourself. I know that sounds obvious, but some people will knock themselves down unconsciously as they describe their skills. If you know you don't have a certain skill they're looking for and the interviewer asks you point blank about that lack of skill on your resume, calmly address where you perceive that weakness to be and how you've addressed or plan to address it.
SMILE.
Interviewers have a tough job too. While it may seem easy (or even fun, for you sadists out there
)to sit in a chair and grill someone with questions, they have to be very observant and they will be seeing a lot of people coming in to interview. The more pleasant their experience with you in the interview, the more likely they're going to remember you when it comes time to move to the next stage (2nd interviews with senior management or the hire itself). I've seen way to many people come in stone-faced and stare at me like they're bored or angry or half-asleep.
Ask the interviewer at the end of the interview if/when to expect a response (positive or negative) and also how best to contact them with any further questions about the position. When they state their preference for contact, remember it. If they say email, then when you get home from the interview (or the next day), email them and thank them for seeing you and express your continued interest in the position and that you look forward to hearing from them.
Overall, since you've never had a job before and you're 26, it will be tough, unless you've got a lot of skills/degrees, etc. But just stick to your guns, show them what talent you have in oral communication, sell yourself well. Good luck!
