The DET's speaking items are recorded at home with nobody in the room: read a sentence aloud, describe a photograph, speak about a topic for up to ninety seconds, and answer the longer interview question that is sent to institutions unscored.
There is no second take. A restart costs the seconds it takes, and the recording keeps running. Practise carrying on through a stumble until it is automatic, because the instinct to apologise and begin again is what most students do on their first attempt.
Describe a photo: use a fixed frame. What it is, who is in it, what they are doing, where, and one inference — "they appear to be…". Five moves means you never run out at twenty seconds, which is the commonest failure on this item.
Speak about a topic: two reasons, one example. State your view in the first sentence, give two reasons, and support one of them with something specific from your own life. Specific beats broad every time, and it is easier to keep talking about something real.
Fill the time, but do not race. Speech that is too fast is scored down for intelligibility. Aim for your normal conversational pace and let the structure carry you to the end.
Set the room up first. Face visible and forward, decent light, no notes anywhere, nobody else in the frame. Those are proctoring rules for the whole hour, and a violation can void a completed test — a worse outcome than a weak answer.