Do you really need a Jackson Pollock when an Ansel Adams will do? By default, most inkjets print in color, which means you spend more money on ink. If you don't need to be splashing all of that color ink around, save it. While color may make graphs and charts look more exciting, in many cases, the information will still be clear in black and white.
When you click print, most software programs will open a print dialog box that's full of various printer settings. Sometimes, switching from color to black and white is as simple as ticking a checkbox on that screen.
Other times you may have to click a button for your printer settings and do a little digging through menus. You'll see options for paper size, orientation and the like. You'll also see a menu that lets you change from color printing to black and white, monochrome or grayscale.
Some printers still use color ink to create blacks, but by switching out of color mode you'll reduce your ink use and save a few cents.