Heh.
I was a hall director.
I can tell you how we interviewed for our RAs, but really all we looked for was someone who was themselves, who could handle a crisis calmly, and someone trustworthy.
Remember, you may have some sleepless nights because of things happening in your hall, and you have to balance that with your classes. If you aren't doing well with your classes now, don't expect your GPA to go up when you're an RA. You're also required to put on programs for students...so come up with some ideas on how you can motivate your floor.
I'm giving you some of the downside, because it's not just a free meal and a free place to stay, and all. You really, really work for that free stuff, and sometimes all that "free" isn't worth the cost of the job.
You will have roommate conflicts. You will have some druggies or alcoholics. You will have some who snap. You will be cleaning up puke in the stairwells (sorry, it happens). But your HD will train you, and you'll learn how to deal with difficult situations.
And yes, it can be a lot of fun, too.
I think it's more of a position for extroverts, but it can depend if you're in a study residence hall, or a freshman dorm. The freshmen dorms are CRAZY.
But if you want the job, be yourself. Tell how you've motivated people, and how you'll make your floor "yours." Explain how you want to help freshmen (or students) acclimate to college life, and that you're willing to go the extra mile.