How should I handle the salary question during a job interview]?

If you're asked what you're  earning, tell them. If you're asked how much you're looking for tell them you want a fair offer.

Hi,

That's definitely a question worth preparing in advance. Find out salaries for identical or similar jobs else where. It will make a great reference point. Don't be shy and show self confident if you decide to ask for more.

I think you should try to find out how much the company pays for a position similar to that you are applying for. (if you have access to this kind of information). On the other hand, when you go to the interview do not ask about the salary, let the interviewer open the subject.You should also take into account your experience,the positions you held up to that moment, and your past salaries.

why do you think you are qualified?

What is relevant here is finding an appropriate job against which to benchmark the open position. Find a market price for the job you're applying for, then determine how close to that median you think you should be paid given your experience and accomplishments. What you made yesterday doesn't matter - what your colleagues and peers are making today does.
Once you've found what the job is worth to the market, save the information until the employer has made you an offer. You will have a good sense of what they will have to pay to meet the market, and you'll be on the firmest ground if you negotiate from that informed position. If the company tries to get you to say what you've been making at any time before making you an offer, use it as an opportunity to showcase your diplomatic skills. Then steer the conversation back to the value of the job to them.

Try to skip these till the last interview round.
discussing the salary during an interview is quite complicated. I suggest to read the following article about salary negotiation during the job interview.
How to Negotiate a Job Offer: Salary Negotiations tips

read more here - job interview guide - job interview site

While you get prepared to answer such questions try to understand the employer's reasons for asking it. Most employers tend to use such questions on past salary as a gauge to determine your market value and read your mind as what you wish. They want to sense what salary you would be expecting from them and whether they would be able to pay you that much or not. At times it is better to disclose the salary to save wastage of time. If the employer finds it more than what he could pay for the position it is better to end the discussion and move ahead.