When applying for a job they sometimes ask what your base salary was at previous employment, they they ask what your current salary requirements are, what is the best way to answer that question? I don't want to give them a number that is too high that weeds me out of the interview pool or too low that I regret it later.

The ONLY way to answer such a question is honestly.

INTERVIEWER: What did you make at your last job?

JOB HUNTER: “This position is not exactly the same as my last job. So let's discuss what my responsibilities would be here and then determine a fair salary for this job.”

From The answer to the toughest interview questions | Penelope Trunk Blog