How to draw a line people can follow
Each row is one position on the horizontal axis, in the order you want the line to run. Do not sort a line by value. Sorting would connect March to January because the numbers are similar, which is a false path. Name the axis. Month and Sessions are clearer than leaving the reader to infer the unit from the title alone. A second series is a comparison through the same positions, such as this year beside last year. Both series must use the same unit.
Straight segments tell the truth about what you measured: you know the points, and the line between them is only a guide. A smooth line is a drawing choice. It looks calmer and it invents bends you did not measure. Use smooth for a gentle overview. Use straight when a peak or a drop is the point of the chart. Points mark the real observations. Turn them on when the measurements are few. Turn them off when the line is dense and the dots become noise.
The vertical range should include the variation you care about, and it should not crop a line. Leave minimum and maximum blank to fit the data, including zero if the data cross or touch it. Set them when several charts in one report must share a scale. A line chart may omit zero more honestly than a bar chart, because the reader is following change rather than judging length from a common base. If you omit zero, the subtitle should not pretend the chart shows total size.
Value labels are useful on a short line and cluttered on a long one. The grid is a help when someone will read a value off the picture. Colors separate series. Two lines in similar gray will merge in a print. The legend must use the series names you typed, so name them before you export, not after.
Download PNG for a slide, PDF for a page, and JPEG if the destination demands it. If the story is the amount accumulated under the line, switch to the area chart. If each point is a pair of independent measurements rather than a step in a sequence, switch to the scatter plot. The sample is stored in this browser only. Clear it with reset, or replace every label before you publish.