First, recognize that you may have an initial screening interview by phone or by camera using the internet. Preparing for either is different than preparing for a face-to-face meeting. In these types of interviews, you have to be prepared to backup what you documented on your resume (because the interviewer is fact-checking) and you can practice being direct and succinct in your answers. Also be sure to limit your surroundings if you are having either type of interview. It doesn't look or sound very good if someone (especially a child or pet) interrupts you during your interview. Make sure to communicate with everyone that you are off-limits during this time so you can devote your entire focus to the interview.
Once you have made it past the initial screening interview, it's time to decide what you are going to wear to the interview. In the past, it was easy to dress for an interview. Men and women alike wore their best blue or black suits, carried a nice briefcase, several additional pristine copies of their resume, and any additional documentation needed (like writing samples). Today, it is much harder to gauge what to wear. Go to the company website and look at photos of how the employees dress. Are they in formal business attire or are they in shorts/t-shirts and jeans? While you do want to look nice and neat at the interview, wearing a black business suit from 1990 will not cut it in an environment where everyone is wearing shorts to work. You will look dated and unable to change which makes it much less likely that you will get hired.
In that a very casual working environment, it is suggested that you wear a nice pair of slacks or a skirt, a matching blouse, and professional but stylish shoes. (If you are retired but looking for a job, it's important to look up-to-date without trying to look 20 years younger). A great way of dressing for job interviews these days is consignment stores. They often have wonderful clothes at a discounted price and often have very helpful sales people who can help you pick out something that flatters you and your budget.
In conjunction with preparing your wardrobe, you have to be ready for some tough interview questions. There are a variety of ways to prepare for these questions on the internet. Be sure to take the time to review them and formulate your own answers to questions like "What was the last project you managed and what was the outcome? Or "Give me an example of a time that you failed. What did you learn from it?" A great place to start for a list of 100 potential interview questions is Monster.com but there are many others as well. If you can practice your answers out loud with a friend or former colleague, you'll be even that much more prepared for the actual job interview.
It's the day of the interview and you've arrived at 15 minutes early. Take this time to use the facility, to freshen up and relax. When you go into the interview, remember that you are well qualified for the job and in your answers, you will highlight your accomplishments and how you solved problems in the past. You can also highlight your ability to adapt to new technology and the changing business climate. Certainly follow-up the interview with your own pointed questions to make sure that this job would be a good fit for you as well.
After the interview is over, treat yourself. Whether you get the job or not, you deserve a pat on the back for even reaching this important step. Then, take a minute to review what you did well and what you can improve on the next time. Also, take the time to write a hand-written thank you note. This is a step that is overlooked by most people who interview these days and it is one more way for you to set yourself apart from the crowd.
Now that you have the first interview under your belt, you will find that this success will most likely build on itself either with a job offer or with additional job interviews. Great news is that you are prepared for either!