When looking at an IELTS writing task 1 chart question, you should ask yourself 10 quick questions before you write your answer.
What kind of chart is it? (Line, pie, bar)
What does the title say about the chart? (Read it carefully)
What information is contained on both axes?
What are the units of measurements? (Age, %, amount etc.)
What groups are compared?
What is the time period? (Past, present or future)
What is the most obvious thing that the data shows you? (General increase or decrease?)
What is the most important or significant piece of information displayed?
Can any comparisons be made? (Between groups or charts if more than one)
Is it a static chart or dynamic chart? (Static- one time period. Dynamic- over a period of time)