Color is not, contrary to popular belief, a guarantee that a document will be appealing. In fact, some documents look better without color. As a general rule, color should be used on no more than one third of a page – and almost never for text.
Color works best as a separator. Using color for thick lines and small artistic elements works well, without over-powering readers. Learning to balance the use of color comes with experience.
Even if you plan to send a document to a full-color commercial printer, there is no need for every photograph to be in color. If you have ever looked at an Ansel Adams or Scott Mutter photo, then you understand that black and white can have a strong impact on viewers. Photographs that highlight textures and patterns are often more effective in black and white.
Give a lot more detail....