Writing task 1 requires different writing skills to those of writing task 2.  This is a short task, which is why you must select and summarise only the key ideas in the visual information.  There are several important points to bear in mind for Academic writing task 1.  To illustrate these, look at the following writing task 1, which appears on the official IELTS website: www.ielts.org:

This next image shows a sample answer I have written for this task.  The comments in the margin highlight the features you must pay careful attention to when writing this type of answer yourself.

Deliberate practice for writing task 1

To practise, begin by studying the language and the organisation I have used.  Then, write your own answer – don’t worry about the time limit when you are building language skills.  Check your answer carefully for any of the common problems mentioned in chapter 6 of  The Key to IELTS Success.  Then compare your own answer with the answer above.

If you want to know how to write an answer to any task 1 question, my Key to IELTS Writing Task 1 book will take you step by step through the thinking and writing process to make sure that you give a clear overview, organise your information well, and highlight the key features.