Official Consular Question:

The #1 rule of answering this question is doing your research on what you should be paid by using site like Global Guideline. You’ll likely come up with a range, and we recommend stating the highest number in that range that applies, based on your experience, education, and skills. Then, make sure the hiring manager knows that you're flexible. You're communicating that you know your skills are valuable, but that you want the job and are willing to negotiate.