Tip #1: Speaking: Describing an Image
The Official Site has offered very general advice on this sting one should "Describe the general content of the image, then summarize the most significant points, referring to details for support" This statement needs to be flushed out into specifics:
The general content of the image means "what is this an image of? "Starting by saying what the image is, what is measured and what the general communication message is before getting into specifics.
Eg This is a graph showing fitness membership sales within a 30 year period from 1970-2000 and compares men and women memberships every 5 years . The goal is to see which times were highest for membership and how men and women differ.
Now that you have the general "what's there" issues and the general purpose, you can then move to the general conclusion. That general conclusion is without specific times or numbers but should answer the purpose
Eg "The graph clearly shows that men seem to fluctuate a lot according to the time period whereas women are a bit more stable"r
Now give specifics to prove your point:
Eg For example, from 1970- 1975 membership by males and women but for men membership dropped by about a third by 1980 while female membership dropped only slightly. There were slight fluctuations with men slightly decreasing and then increasing 1980 to 1990 and women slightly increasing and then decreasing. But a big change for men occurred in 1995 when membership more than doubled whereas strangely women only rose slightly. Then for some reason in 2000, membership dropped substantially by 2000 whereas women only dropped slightly.
Make a speculation as to why this is:
It may be that membership of men is more related to economic or social condition of the time, whereas women are more likely to have a stable value for it but it's hard to tell unless more research is provided.