Silence is judged more harshly than hesitation
A long silent pause while thinking makes a listener assume you don''t know the answer. A short filled pause — "well", "let me think", "that''s an interesting question" — signals you are actively processing, not stuck. The content of what you eventually say matters, but so does how you occupy the gap before it.
Useful, natural fillers
To buy a few seconds: "that's a good question", "let me think about that for a moment", "well, actually". To rephrase something you started badly: "what I mean is...", "or rather...", "in other words...". To return to a point after a tangent: "anyway, going back to what I was saying...". These sound natural because native speakers use them constantly — they are not a sign of weak English.
What to avoid
Overusing a single filler like "um" or "like" on every sentence draws attention to itself. Rotate between two or three of the phrases above instead of defaulting to the same one every time you need a second to think.
Practice
Record yourself answering a question you haven''t prepared for. Listen back and count how many silent gaps you left versus how many you filled naturally — then try the same question again using one of the phrases above every time you need to pause.