You have to calibrate your monitors AND your printers. Basically you need one of these:
X-Rite: CMUNDE : ColorMunki Design
It installs a utility on your mac and will have you rest the device on the display (it comes with a strap that has counterweights so it'll just rest on the display on its own.) The utility puts the monitor through several color changes and the calibrater notes the accuracy of the actual color vs. the intended color. It then builds a color profile for THAT specific display and saves it on your Mac along with all the rest of the profiles (in "System Preferences" -> "Displays" -> "Color"). The utility that comes with the display performs the calibration and creates the profile and they also have an option that will remind you to re-check the display calibration from time to time (although LED backlit monitors seldom drift much.)
The same device also calibrates printers. Printer calibration is *slightly* trickier for two reasons:
1) Every different type of paper will require it's own color profile. Change paper brands or types... and you have to make a profile for that specific paper.
2) The same goes for ink. If you ever use a different ink then you'd need a profile for that specific ink.
3) Printers and computers usually have some color profiling built in. Basically you need to make sure that when you profile the printer there is either (a) no profile active at all -- neither in the printer nor on the computer or (b) if there is a profile, it needs to be neutral (not trying to alter the colors.) That's because the color profile the Colormunki will build expresses how much the colors need to be altered from the printers native colors to produce the accurate color. It assumes the colors coming out of the printer are the native colors.
The Colormunki will print a page with color strips on it and you'll slide the device down the strips following the on-screen prompts. The first page is standard (it always prints the first set of colors). It'll then print a 2nd page after you finish scanning all the strips on the first page. This second page will focus on areas that the Colormunki felt needed more correction and testing. At that point it creates a printer profile and installs in the standard Mac locations (you can find these by going into Finder and navigating to Applications -> Utilities -> ColorSync Utility and then select Devices -> Printers.
You'll notice when you pick a printer there are LOTS of profiles for each printer. But if you highlight each one while looking at the panel on the right, you'll the paper type is different for every profile.
When you print on a Mac, there's an optional "Color Matching" category and you can pick the color profile you'd like to use. Select the appropriate profile based on the paper and ink you happen to be using at the time.
Good luck!