Be open, realistic, and honest. Transparency is the best choice when salary-based questions arise. Use your current earnings as a baseline. Share anything that impacts your cost of living - bonuses or incentives, your commute, retirement packages, stock options, PTO, etcetera. Then project what your income would be over the next year or two, including how frequently you received performance reviews. Once you've done this, find out what they offer. Once you find where they're meeting, exceeding, or wanting in this regard, you can adjust your number accordingly.