Well, in a nutshell, examiners want to see you speaking confidently, fluently, and intelligibly. But they are going to gauge your speaking abilities against a rubric, which the British Council makes public here. Familiarize yourself with this rubric.
The four sections of the rubric are all graded equally, which means that 25% of your score will be based on your grammar skills, 25% on your vocabulary, and so on.
Let’s look at each section individually...
Fluency and Coherence
When you respond to the examiner’s questions or speak about your assigned topic, you will be expected to speak effortlessly (fluency) and in an organized manner (coherence). In other words*, you will need to speak quickly, and your points must connect in a way that makes sense to the listener.
Essentially a fancy way of saying “vocabulary”, this section tests for variation in your English language ability. Use a range of words and phrases to show that you have a sufficient vocabulary to be fully understood.
Grammatical Range and Accuracy
The examiner will be looking for you to use grammar that is correct as well as appropriate for what you are saying. You will be expected to vary your sentence structures.
Of course it is important to be understood. The examiner will be paying close attention to your word and sentence stress, intonation, and overall intelligibility. It’s okay to have an accent, but you must speech must be clear.
*Notice my use of the phrase “in other words”? This is a great way to introduce paraphrasing.
Feature image courtesy of Victor U of Flickr