When taking a speaking test. Here are some guidelines to follow.
Have a loud and clear voice so that the invigilator can hear you well.
Give descriptive words. Instead of saying "It's a good cake", try saying "It's a flavorful cake".
Don't give too much or too little information about a topic.
Don't try speaking too slow or too fast. You have a time limit.
Make sure you are not going to another topic rather than the one they are asking.