At the end of my interview, I was asked what my salary requirements are and didn't know what to say. How do I answer this?

A rule of thumb for salary questions and negotiations: Try and get the employer to give you a salary range first.  If your figure is too high, you risk being seen as unaffordable.  If it's too low, you may be seen as less than serious.  

If you can get the employer to offer at least a range initially, you can start working on negotiating an offer that falls (ideally) in the upper part of that range by backing it up with data from general salary surveys, F&ES salary data, geographical cost of living considerations and your personal bottom line, i.e. what is the minimum you are willing to accept so that you can maintain or afford your life?  

If the job is a once-in-a-lifetime opportunity that will benefit your career in other ways or has an ideal schedule with the kind of flexibility you want, you may be willing to accept less.  If it is one of several offers all equally attractive, you may want to select the position that satisfies more of your personal work/life needs, is in the ideal location or will offer you the most professionally.

This is a common question!  In her blog column, The Brazen Careerist, Penelope Trunk addresses the intricacies of this type of negotiation/discussion in The answer to the toughest interview question.  Check it out!