Before you describe a picture it is very important to take a look at the picture and think of any interesting and useful vocabulary you may use. If you have time to prepare it in advance it might be advisable to write down your description, or at least the key sentences.
Who? where? what (are they doing)?
Describe people, physically, mood, clothes, also the place, weather...?
What happened/is happening to the place or characters?
What will happen next?
How do you feel about the picture? how do the people in the picture feel?
Debate (for couples)
EXAMPLES AND MORE TIPS. https://www.slideshare.net/ang_ruiz/describing-a-photo
It looks like
In the background/foreground
In this picture I can see
it seems to be...
I think that / In my opinion...
they are probaby...
It's hard to tell but...
let me think for a second...
other linkers (however, on the other hand, etc.)
Activity. Read and watch a piece of news from the following page. http://www.bbc.co.uk/learningenglish/english/features/witn
Then debate in class about it and describe the pictures that accompany the article.
CLASS ACTIVITIES TO PROMOTE SPEAKING IN ENGLISH:
Make a circle, the teacher goes around the circle and touches two people on their back then he gives them a topic and asks them to discuss about it for one minute. If any of the two runs out of ideas or words for longer than five seconds they will exit the circle. There will be a speech king at the end of the game who will get a positive mark.