How should I rehearse the salary part of an English interview before the call?

Rehearse the question, not only the answer. Three takes are enough: one read from the script, one without the paper, and one where someone asks at an unexpected moment and in different wording. Listen once for content and once for pace, then check that the number in the recording is the number you meant to give. Practising alone, a mirror and one recording will do; the value is in the second take, not in a perfect first one.

Put the script under three different question shapes before the call, because the words you hear on the day are rarely the ones printed anywhere: a question about your salary expectations, a question about what you are looking for in terms of package, and a blunt question about the number you have in mind. Ask someone to pick one at random, and to stay silent for five seconds after your answer - most candidates fill that silence with a discount. Record one cold take at the start of a session, with no warm-up, because the real call arrives without one.

The Salary Question in an English Interview: What to Say When They Ask →