There are 4 necessary elements of form and function that your print layout should contain:

1) KISS [Keep It Simple, Stupid]
It is tempting and quite common to overdo design work, from a simple logo to a complex marketing campaign. But the simple truth about what make design better is just that: Simple. The more you add to a design, the more you take away from its focus, let alone the integrity of the design as a whole.
2) Consistency
Establishing and maintaining a consistent "look & feel" when designing is paramount to its effectiveness. The more consistency, the more the viewer remembers. It is especially true when designing a group of pieces, such as a Corporate Identity Package. You are not only designing a logo, but all collateral material that will support it, from business cards and letterhead to catalogs and advertising. Fonts, colors, art elements, even the style or "voice" of the copy must always remain consistent.
3) Stuff, and Fluff
In every design piece, there are the purpose-related pieces of the puzzle such as logo and supporting elements, and there are the pretty bits that support them like color, photography, etc. Establishing a focus on the important elements can determine the success of a design. This is done by organizing information, both visual and verbal, in a hierarchy.
4) Refrigerator Time
Before sending a design to a client or printer, the piece should be painstakingly checked for mistakes. But equally important should be the scrutiny of the design itself. That's where the refrigerator door comes in. Hang a printout of the design on your fridg and let it stay there for as long as need be. You will notice many things, good and bad, about it. Once the flaws are fixed, the piece will be perfect and truly complete. And you will be confident in a job well done.

For these reasons it is important to choose a graphic design firm that considers all these aspects. Choose one that is part educator, part artist, and part geek. Choose wisely and good luck!