In my work as a graphic designer I have had the occasion to “fix” poor work prepared by amateurs who are seriously lacking in the knowledge regarding what it takes to make a design printable on paper.
The first issue is design software. Most of the problem files are created in a raster-based (bitmap) program such as Adobe(R) Photoshop. Software like this creates images composed of pixels. As such, they cannot be made larger without losing resolution.
It would be much better if they were to use professional vector-based software that creates objects that may be resized and reshaped without loss of resolution. These include CorelDraw(R), Adobe Illustrator(R), and Adobe InDesign(R).
The next major issue is color. Commercial printers use four colors of inks (cyan, magenta, yellow, and black–CMYK). These are called process colors. Unfortunately, amateur designers tend to create their files in the RGB (red, green, blue) color palette which is suitable primarily for video (slide presentations and websites).
When RGB colors are printed, there are major color problems. The colors do not look the same as they did on the computer screen.
Finally, there is the problem of type readability. Text can be a problem in two instances. One is if the type is too thin, and the other if the type is reversed (white type on a dark background). The image below is a scan of a printed RGB image.
In the printing process, the dark ink tends to leak into the white area, thereby making it thinner than it already is. The solution is to use a heavier weight in order to make the type more readable. It also helps to add more space between characters. Extra character space has been added to the first three lines of text on the right. The image below is a screen capture.