There are two particularly useful shortcut keys when using an Excel chart (graph).
Use Ctrl + Left or Right arrow keys to move through selecting each chart element. From the whole chart area, to Plot area, legend, y-axis, x-axis, title, all points in the series, and then each individual point in the series. Great for getting to the point you want when it is close to others and hard to get just right with the mouse.
Use Ctrl + 1 will bring up the format options for the element you have selected.