guess it depends what job it is and what field?
I find best way is to research the company so you can ask constructive questions.
Also always have 5 or so questions to ask, I hate it when I am interviewing and when asked do you have any questions the answer is no – just feel the person is not that interested.
Remember it is your chance to interview the company representative too as you may not like your potential boss.
I have walked out of a number of interviews as I thought there was no way I could work with/for this person and haven't regretted it.
Good luck and let us know how you get on 😉