Well I'm a designer so I may see things that a non-designer wouldn't pick up on. The first thing you want to do is to see printed samples of their work. This is

Well I'm a designer so I may see things that a non-designer wouldn't pick up on. The first thing you want to do is to see printed samples of their work. This is a test not just to see the work itself, but to see how quickly they get it to you and if they follow up after it's been sent. When you're looking at the printing see how black the blacks are — are things trimmed well? How are their communication skills? Also a must have for me is the ability to see a printed proof — looking at an acrobat file on a computer screen is a waste of time.