Using a gray card to color balance in photoshop
A simple gray card helps make color balance adjustments in Photoshop easier
If you're reading this. I assume that you're not happy with the steps or results you get with your present method of getting colors to balance. There are many ways to get good color. The following is just one way, but it requires a little preparation. You will need a photographic gray card in your camera bag to make this work, and use this card BEFORE shooting your photos.
Buying an 18% gray card
You can get a gray card from your local camera store OR www.amazon.com has 1 Gray Card 8"x 10" for $5.49. Amazon did not say "18%," but since it was sold at a camera store, chances are it will work. Otherwise I saw on the internet a few cards (2) for $18-$20 that were 18% gray.
Using the gray card
Before the "camera shoot," get your best angle and distance to the subject; then place the card in the scene, tilted slightly towards the light source and take a photo or two. Provided the light remains the same, and your angle to the light as well, this photo will be the key to balancing the batch of photos you shoot.
Your camera may have a "internal balance" that can be set via a gray card
Check your camera's manual to see if the balance can be set inside the camera using a gray card, but since this article is about using Photoshop, I will move on. BTW: Your exposure can be set using this card as well. Meter your exposure and open the camera aperture a half stop for most scenes.
Back at the office
Load your photos into the computer and open the first photo with the gray card. Go to Image > Adjustments > Curves... Using the middle eyedropper (gray), click in the middle of the gray card. You have just set the neutral gray for your photo. Save this setting (click Save in the Curves dialog box) so you can load it with all your photos from the shoot.