Most logos and letterhead jobs are done in 2 color. Using the 4 Color CMYK process works great for catalogs and brochure jobs with photographs, however not all of these type jobs look better in 4 color. If you are trying to match a logo that has a very vibrant color that uses a Pantone Solid color then often the 4 color equivalent will be off and not match exactly. Make sure you or your designer checks a swatch book to see how the color will shift. Or consider running the job with just 2 colors.
Orange is one of those colors that can shift very badly on a 4 color printing press so be careful when working in this color range. Often the orange colors become muddy. If you are using orange and a dark color like blue you can use blue for your text or add a third color - black. If you have photos they can been turned into duotones to achieve a nice look. If you really need to use Full Color Photos and match a specific color to a logo or a particular Pantone swatch then you may have to go to a 5 color process, however this will increase your print costs. Another technique is to bring in a metallic Pantone color.