While you may have state-of-the-art equipment and experienced, professional employees, if you do not have great artwork, your business will still lack a key component to succeed.
Shops face many challenges in this aspect, from having no art background themselves to facing increasing pressure to get jobs out quickly.
Time is money and artists are selling time. How much a piece of artwork costs is more or less dictated by how much time it takes to create it. Experience is a close second. A more experienced artist is going to charge more per hour than a less experienced one. However, this higher cost may be offset by the more experienced artist being faster and able to produce a higher quality design that the customer is more satisfied with. So those are the tradeoffs to consider.
The more specific customers are and the more unique the look and style that is wanted for a design, the more time it will take to create. It is easy to lose money trying to figure out exactly what customers want and going through revision after revision until you finally have a piece with which they are happy. To avoid this trap, ask lots of questions, show lots of examples, and force the customer to approve artwork in writing. You also should limit how many “free” revisions you will do. A common policy is to limit the number of revisions for the included price, and after that, they will be charged at the normal hourly rate.