From your personal experience; what are the best tips you can give to owning a job interview ?

Prepration 

first of all you need to cafefully study the organization you are applying to work with, you may visit thei web site, ask some friends, by this study you make sure you understand the goals of the organization, core values and it's hirarchy, it's very vital to show them during the interview how much you're interested to join their team by knowing these things.

you should have an updated CV, a list of references, and recmoomendation letters if you can.

be prepared to answer questions regarding your previous experience, these questions usually are not answered in you CV. recently organizations are very keen to use competency based interviews, therefore you need to analyze the job you are applying for to determine what are the most required competencies a person should have to perform effectively in the job, arm your self with strong situations from your past to prove you have the competencies and you are using them. read about interviews and expect some common questions in the interview like why do you want to leave your current job? or Why should we hire you?.

finally and most important: BE YOUR SELF. don't be shy for being nervous, but try to focus on the questions, Don't answer questions you couldn't understand, instead, ask for an explanation. show the interviewers how much value you will add to their team by focusing on your strengths, skills, knowledge, competencies,