1. It's all about the phrasing.
A lot of employers ask you questions just so they can see how carefully you will respond. Most jobs will always ask you for your biggest weakness. The best way to show them that you have things you struggle with but are a great candidate for the position is to respond by phrasing it in a positive way. Rather than saying "my biggest weakness is..." you can say "the area that I would like to improve upon is...". It makes you appear confident yet aware you can always improve.
2. Dress to impress.
It's ALWAYS better to be overdressed than underdressed in an interview. Whether the position is for a marketing firm or a dentist office, dressing to impress is a real thing. If you present yourself in a professional manner, the employer is going to view you as someone who would take the job seriously.
3. Always bring multiple copies of your resume.
You never know how many people will be in your interview. Sometimes there will be one, other times there will be multiple people from the company. Nothing looks worse than being unprepared, so always bring multiple copies of your resume. It's important for everyone in the interview to have a copy when you're applying for a job. Plus it makes you look like you're organized.
4. Do your research.
Know facts about the company you're applying for a job at! All it takes are a couple google searches to find some good facts and information about the business to bring up during your interview. Not only does it show that you're prepared, but also that you are interested in the business as a whole and know exactly what you're applying for.
5. Ask questions.
Always, always, ALWAYS come up with questions to ask. It makes you appear engaged and interested which is something employers look for. It also shows that you are interested in learning more about the position and business.
6. Give a good handshake.
There is most definitely a perfect handshake, and nothing screams unprofessional like a weak one. It's important that you go in strong and confident.
7. Make eye contact.
Making eye contact with the person you are interviewing with is super important. It shows that you are engaged and most of all paying attention to what the employer is saying.
8. Proofread your resume. Then do it again.
One spelling error immediately will get your resume thrown away. Employers are looking for someone professional, and that means someone who will spend the time looking over their work to make sure it is error free.
9. Remember their name.
When you're leaving the interview, always thank them for their time and mention their name. It creates a personal relationship which is really important when applying for a potential job. It also shows that the interview and employer are important to you.
10. Always send a follow up card thanking them.
A hand written card is a great, personal way to thank the employer for taking time to interview with you. Make it personalized to the person you met with, let them know how much you enjoyed meeting with them, and say something that makes them remember you and think back to your interview. It creates a relationship and is a thoughtful way to let them know you are interested in the position. If you want extra brownie points, deliver it in person to the office.
Research work they have done in the past to mention during your interview.
Interviewing for a job at a research lab? Advertising company? Talk about a discovery or a campaign they had done in the past that inspired you! It makes you look as if you have been interested for a long time and already have a connection to the business which would make you a great candidate. It also makes them feel good about their successes and will make them more engaged in the conversation.