Mathematics Teaching in the Middle School 9 (6), 340-343
Y axis should start at 0
Your graph's y-axis should start at 0. A torn graph (y-axis does not start at 0) can create the impression of significant change where there is relatively little change.
You can use break lines to make your graph looks less empty.
Label your graph
The graph should have labels for both x-axis and y-axis. Assume what is obvious to you is not necessarily obvious to your audience. For example, if the data for your x-axis are years, you should label your x-axis as "Time (year)" or "Year". The numbers can mean different things other than years.
Use correct colors
If the same conditions apply to all graphs, use one color for each condition and keep it for all the graphs.
Use simple graphs
For your research presentation or paper submission, it is recommended to use simple symbols such as circles, boxes rather than complex icons or logos.
Legends should be incorporated into the white space in the graph. If there is no white space to put the legends, the graph is too busy and the main message is being lost anyway.