Do this quick test?
Look at the picture in the link below for two minutes. Then on a piece of paper write down a physical description of one (or more) of the characters that you have seen.
Picture
How did that go? Did you include a lot of detail? If you want to practice some more, here are some exercises from agendaweb.org. On this webpage you will find lots of different exercises to do. Below are exercises that ask you to practise describing a person's personality or physical characteristics.
A2 exercises
B1- B2 exercises