Grayscale Workflow:

When designing for a standard priced CD booklet, one full side (outside) will be quoted out as color while the other side (inside) is black and white or grayscale.

Top row is color (4)
Bottom row is B&W (1)

Standard quotes always include 4/1 printing
4/4 printing is considered an upgrade (extra cost)
 

You can pay extra to get color on all sides of your booklet, but for this section of the tutorial we will assume you need standard B&W artwork or grayscale images for the inside of the folder. This standard configuration is called 4 over 1 printing. 4 being the CMYK color and 1 being grayscale using black ink.

Grayscale can be achieved using
the black channel only in CMYK printing-

Grayscale Definition:

RGB Grayscale mode uses up to 256 shades of gray. Every pixel of an RGB Photoshop grayscale image has a brightness value ranging from 0 (black) to 255 (white). Grayscale values for printing CMYK CDs and Booklets will be measured as percentages of black ink coverage (0% is equal to white, 100% to black). Gray spot colors are available with such names as "cool gray" so be aware that these still constitute a "spot color" which costs extra if used on any paper parts.

• Any image can be converted to grayscale. (Provided it opens in Photoshop)
  
  
• To convert a color image to a high-quality grayscale image, Photoshop discards all color information in the original image. The gray levels (shades) of the converted pixels represent the luminosity of the original pixels.
  
  
• You can mix information from the color channels to create a custom grayscale channel by using the Channel Mixer command.
  

What about stapled booklets?

Just like folders, booklets are also classified as 4 over 1 or 4 over 4. The outermost covers, say pages 1 and 8 on an 8 page stapled booklet would typically be colored while all inside pages, 2 through 7, would be B&W or grayscale.