Many people struggle with setting their white balance to be accurate in their photography. Using a black, white and gray card is a super quick, easy and inexpensive way of making sure your colors turn out accurately. This is a no brainer, for anyone who uses Photoshop, and shoots professional photography.
Here is a link to show you the process: http://digital-photography-school.com/get-your-white-balance-right-in-seconds-using-grey-card/
Here is a link to an inexpensive black, white and gray card for purchase: https://amzn.com/B012TI52FS
As a general summary: Shoot the cards in the scene with your subject, then shoot without the cards as you normally would. When you are in Photoshop, add a levels adjustment layer, set the black white and gray eyedroppers to those colored cards in your photo. Voila!