Find that one thing that makes you stand out from all your peers and tell me about it. I want to employ a person who is going to bring something new and maybe even unique to our organisation, whatever it might be. Decide what you have to offer. Be prepared to talk about this.
Most companies now have a website that contains it's structure, vision, and goals.
Find out what their core business is and determine how your skills will assist them to achieve the goals. Use the selection criteria to anticipate the questions. By that I mean that we want to see what kind of contribution they have made to the world, how they have spent their spare time etc. So, as far as tips go, I question the applicant as much as possible about their interests, what they do in their spare time, etc. This will give you an indication of the motivation level and dimension of the applicant.