Happy goth has some great advice above.
I would just like to add one point. See the interview as your chance to tell any company why they need YOU. We get many applicants, tell us why to hire you instead of the other applicants. The worst answer to “why do you want to work here?” Is: I need a job/it looks fun/I like Target. Seriously, this question is NOT about you, it’s about what you can do for Target. Tell what you bring to the table, what you can do FOR Target that no one else can. Sell yourself, what are your skills, strengths.
One more heads up: a big turn down reason for me is excessively complaining about your previous employer. It shows you refuse to take any responsibility for leaving your last job, placing all blame on others. Even if it’s true, don’t excessively complain.