If you are working with a recruiter and he/she got you the interview, you should ask them what salary range the firm stated for the position; and then share the high end of that range. This way you can negotiate toward the middle of that range, if necessary. If you’re applying directly and don’t know a range, it’s advisable to ask for something slightly north of what you’re currently earning, maybe 10% to 15% higher. This is not a "frothy" market for the jobseeker right now, and you don’t want to price yourself out of contention before you’re even selected to interview.
Always go to an interview prepared to answer this question. Do your research. Look up the position you are hiring for on wwwsalary.com. Find out what the average pay is for the position for your educational level and level of experience. This way you can answer "Based on my research, I’ve found that the starting pay for this position for someone with my education and experience is between (blank) and (blank) and I’m comfortable with that." This way you showed you did your research, you came prepared, you still answered the question without committing to an exact number leaving the door open for negotiations.
I beg to differ when working with a recruiter. A seasoned recruiter should never offer the salary range in the initial conversation. Yet the recruiter should ask (and this is legal):”What do you need to see in your salary to keep yourself whole and how did you arrive at that number? That will tell you a LOT! The answer a candidate should give should be a range that goes from X to X +10%-15%. The X number, should be a number you can live with, (just in case it goes low). The response back from the recruiter should be something along the lines of “that is in the range”, should we be still talking? Note, the recruiter still has not told them the salary number. I consistently place candidates at companies and they don’t know the salary they will be getting until the offer comes in. And I get 100% acceptance for a job, when a candidate is given an offer. A rookie recruiter, may say the what the pay is (an example $125K-$150K). Problem, then is the candidate hears the $150k and the CFO hears the $125K. Result-no hire or bad feelings, which is not how you want start or end the conversation.