There are a lot of great tips out there that can serve a job-hunter well but there are also a lot of bad tips to wade through. Over my career I have likely interviewed thousands of candidates and consulted with hundreds (if not also up to a thousand or more) job-seekers. Certainly, as a Body Language expert I could offer you suggestions as to your posture, eye contact, gestures, positioning... but, quite honestly, most people are concerned enough with having answers to the interviewers questions to concern themselves with this level of detail.
Instead, I'd like to share my all-time, Top 5 Tips for ensuring that your interview is a success. These five things will help you to stand out from the crowd and be favourably remembered. Each tip gives you a slight and subtle edge that is often more than enough to distinguish you from others and help to position you positively.
Tip #1. Arrive early and be Prepared. I know that this seems particularly basic but it is surprising how few candidates follow this tip. Do not put yourself in the position of having to explain why you were delayed. The interviewer doesn't know you yet, which means they don't care about you, which means they simply don't care. Plan ahead. Know your route. Leave more than enough extra time to cover for all contingencies. As for being prepared... do NOT think that you know yourself well enough to 'wing' an interview. If you have not been out job-searching for a while then you need to spend some time determining what stories you will share, what accomplishments you will highlight. Think about the job in questions and determine what you would be looking for in someone for that role, if you were the interviewer, and ensure that you are able to address those needs. Finally... in this age of the Internet and Google, there is no excuse for not being familiar with the company. You should have done a search on the organization, on the interviewer and read over the company website from beginning to end at the very least.
Tip #2. Don't oversell, but don't undersell. People often skew too far in either of these directions. Share your stories clearly, succinctly and comfortably. You are speaking about yourself, so you are speaking about something you know well. As a result, your voice tone will convey; knowledgeable, confident, and comfortable. Let that work for you. If you oversell you will sound pushy, arrogant and possibly desperate or unbelievable. Underselling will serve to make you forgettable. Instead, consider that you are sharing facts, information that you know to be true. This will always sound genuine, natural and believable.
Tip #3. Take on the role of the Host, not the Guest. As soon as we go out to spend time with someone in their offices we unconsciously adopt the role of a Guest. As a guest we are focused internally, on ourselves, and expect others to make us feel comfortable. The other party now assumes the role of Host and is responsible for us. This is perhaps fine if our interviewer is an extrovert and likes making small talk but the odds are not in favour of this being the case. You now are just 'work' for them and they are beginning their time with you from a place of discomfort. Additionally, as a guest, you are now focused on yourself, your needs and your comfort. You are 'in your head', assessing your answers, whether you've done a good job, what the interviewer is likely thinking about you, how do you seem to be doing. All of this internal dialogue typically leads to external behavioural 'leakage' which serves to undermine your delivery of strength, confidence and credibility. Instead, subtly take on the role of Host. Initiate the handshake and the small talk. Work to make the interviewer feel comfortable. Stay out of your head and continue to focus on their comfort. This external orientation means that you are not in your head to hear your 'inner voice' (which rarely is being supportive) and therefore your behavioural leakage will be more controlled and comfortable. It is much easier to control the focus of your mind (and therefore the behaviours) than it is to try to manage all of the behaviours!
Tip #4. Yes... clothes matter! Give due consideration to what you plan to wear, prepare it ahead and make sure it is in order. Hems are up, shoes are polished, buttons are in place, everything is clean. Again, this may sound as though this is a given but, trust me, many candidates often seem as though they simply rolled out of bed and jumped into whatever was handy. You should also ensure that the outfit or suit you are planning on wearing fits. The morning of the interview is not the time to discover that the suit you haven't worn in six months fits the body you had then, not the one you have now! Consider also your briefcase and purse because they are also extensions of you. Ensure that they are clean, in good shape and not overstuffed to bursting. Take into your interview only what you need for the interview, leaving the rest of your world at home or in the car. Details like having a pad of paper and pen available (and their condition) are also small clues to your organizational skills.
Tip #5. Follow up. Most candidates only follow up with their interviewer to find out if a decision has been made. In which case, the contact is all about you. To stand out favourably, make your follow up about the interviewer. Certainly a simple note thanking them for their time is a step in the right direction but it is far better to personalize the contact more. Reference a small tidbit of information relating to your conversation that demonstrates you were paying attention to and were focused on them. Even better? Give them something. Provide them with a link to an article or site you thought they would be interested in, a contact to add to their network, a piece of information that relates back to your conversation but that you hadn't had time to mention. For example... "You mentioned that you were going to be travelling to New Orleans shortly. I have a great friend who grew up in the city. I took the liberty of contacting him for some suggested restaurants that the locals know and love but that most tourists typically 'miss'. He recommended you try..." Or perhaps... "Here is the link to that TED Talk I mentioned. I thought you would enjoy it..." It needn't be big, it should have no dollar value attached and should simply show that you were listening to them and were willing to help them in some way. Even if you don't end up getting the job you likely have gained another advocate and network contact.