When time is a variable, make it the horizontal axis. Try to avoid more than three different lines on a graph. Dot charts show correlation and large data sets. Label both axes. Keep the dots fairly small.
Color is often unnecessary in maps.
Label the elements that readers must identify. Gannt charts are often used in proposals. Customarily, bars are filled in when a task is completed, red outlines indicate critical activities that must be completed on time, and diamonds or other characters indicate progress reports, major achievements, or other accomplishments. Be sure to refer to every visual in your text and embed your visual in the text as close to the reference as you can. How much you discuss the visual depends upon your audience, the complexity of the visual, and the importance of the point it makes.