Listen carefully so you give relevant answers.
Answer the questions with some detail, so your answers are long enough and you can show the examiner what you are capable of.
It is better to say something, even if it is wrong than to say nothing at all.
Give examples when talking, when necessary
Don't forget to smile ;-)
Practice ways of delaying answers and using fillers.
Don't worry if you realise you made a mistake, it is fine if you correct yourself, but if you don't don't worry either, just carry on speaking.
Remember to use S third person singular.
Try to use some phrasal verbs.