During the test

If you need time to think about something, try to keep speaking rather than remain silent. You could say things such as:
Please give me a moment while I think about the answer

Try to avoid complicated explanations or grammar if you are not sure about them. If the truthful answer is difficult to explain, you may want to say something easier in the exam. Also it is important to know that everything you say not necessary needs to be true.

If you do not understand what you are meant to do, ask the examiner to explain. For example, you could say:
Could you repeat the question, please?
This does not affect your final score.

At the start of the individual task, talking to yourself: Let me see ... what do these photographs show?
At the start of the joint task, talking to the other student: Shall we start by describing what we see in the pictures?
During the three-way discussion, asking either the examiner or the other student: What is your opinion?

To avoid wasting time, make it clear when you have finished talking. For example, say something like:
That's all I can think of at the moment

These phrases can help you to be more fluent at the moment you are speaking since you do not stop and do long pauses.