Of course you want your photos and graphics to be true color, and if you print, you want them to look good. You want your whites, white and your grays, gray. In order to prevent having an unintentional tint to your project, you should calibrate your monitor. Have you ever wondered if your editing is correct, in the case that someone else on another computer is seeing your artwork the way you intended? I always have and I finally found the answer.
I'm on a Windows PC, running W7. I wouldn't know how to do this on a Mac. Go to your control panel and in the search box type in "calibrate monitor". You'll get two results. Click on "Calibrate display color" and simply follow the instructions. There is a back arrow in the upper left in case you need to return to a previous screen. If you are not sure of the gamma setting in the beginning, use in tandem with Quick Gamma (a free download). Have your control panel window off to the side and Quick Gamma on the other, and you can see the change in Bar A on Quick Gamma. It says to have the gray bar disappear at 1.8 and still gray at 2.2 to be close to accurate. I then closed QG since the control panel was easy enough from there on. If you're on a laptop, your brightness controls are most likely on the keyboard.
Save your settings and continue on to the text adjustment. I highly recommend this as well. You probably thought text looked fine until you sharpen it with this tool. It does effect your images a bit too.
My only issue with calibration is that I do use my computers for other things, like streaming television and games. I tend to mess with the brightness almost daily. I was told to use the limo tint that comes in sheets like window clings since my screen doesn't get hot when in use. I'll have to give it a try. I'll update this post if I see a problem. A screen guard isn't practical for me on either of my computers and are much more money than a roll of limo tint from the auto parts store (I also was told to make sure it's non-adhesive, only clingy).