#5 - RGB vs CMYK vs Spot ColorWhile most modern print RIPs can provide adequate color compensation when handling RGB files for a CMYK output process, the subtle difference in color can, on occasion, cause a headache when color accuracy is key. The bigger problem is when CMYK or RGB is used for spot color handling.
Spot colors are used to define a very specific mixture of ink, like PMS 185, or Reflex Blue. While those colors do have a CMYK equivalent, they must be assigned as spot colors when printing the specified ink. It's sort of like taking a logo that is only black, making a plate, and replacing the black ink on the press with a specific ink, like Reflex Blue.
#4 - Incorrect SizeYes, this one actually happens quite a bit, especially on amateur designs. 90% of the time this happens, the culprit is the program used to design the piece. There are dozens of "cost effective" or free programs that can be used to design artwork. Many of them output JPEG images of the designs, which tend to be both low resolution and an incorrect size.
Another program that is very common (and very wrong to use for print design) is Microsoft PowerPoint. While PowerPoint's ease-of-use can be tempting to design a simple layout with, it nearly always puts both the designer and printer in a state of frustration. The reason is that the default size of a PowerPoint document is 7"x10", which is not properly scalable to a standard 8.5"x11" sheet.
When MS Office programs are all you have at your disposal, the prefered program under the Office umbrella is Microsoft Publisher. While not a substitute for a professional design program, Publisher provides proper tools for page size, as well as resolution settings and the ability to export your art as a PDF file.
#3 - Insufficient MarginsThis one can be seen daily, even in professionally designed pieces. A margin area (not the butter-like substance known as margarine) is a designated empty space from the finished edge to the content of the artwork. It's basically the space that is measured from the edge of the sheet to any type or images that should not be cut off. Without the extra space, the artwork can appear too close to the edge of the sheet, and give the illusion of being cut off or cut wrong, and even risks getting accidentally cut off entirely! The margin area on a typical piece is between one eighth inch (0.125") and one quarter inch (0.25").
#2 - Low Resolution ImagesAnother common mistake that both amateur and web designers make when entering the world of design for print. Web designers are accustomed to working with images at low resolutions, usually because websites use a resolution of 72 PPI (pixels per inch). Many amateur designers also download images from websites to incorporate into their designs, which are often still at 72 PPI.
While a 72 PPI image may look good on a computer screen, it is far from being a print ready image. In order to get a reasonable quality print, images and other design elements must be at least 300 PPI to not appear pixelated. The highest quality of printing processes can print at resolutions exceeding 1200 PPI! Don't worry, there are several places you can obtain high resolution images. Aside from taking a photo with your own camera, stock photo websites have huge stocks of images and designs available, and typically have several resolutions and sizes for each image.
#1 - Lack of BleedsLack of bleeds, or too little bleed are the number one reasons for returning artwork to the customer for revision. Bleeds are an extra bit of art that goes outside the final cut area of a sheet. Anything that comes close to, or right to the edge of the sheet should bleed, or go beyond the edge of the sheet. A bleed is usually between one eighth inch (0.125") and one quarter inch (0.25"), depending on the final size of the piece.
Most of the time, it's an easy fix, seeing as all professional design programs have bleed settings built into the program, and it's just a matter of turning them on or adjusting the artwork. Occasionally, the art needs to be resized, and background elements need to be stretched to allow for proper bleeds. Sometimes, the margins are big enough that the artwork can be stretched, or blown up by 2% to create a pseudo-bleed.