Creating a print ready file is the key to getting the job you are looking for.
Lets assume you are using a piece of commercial design software such as the Adobe Suite or Quark Xpress. If you haven't heard of these programs don't worry select your program on the drop down list on the right hand side for more specific advice, if your program isn't there just contact us we are always happy to help.
Right on with the basics...
The main file format used for commercial printing is the PDF, with the ability to view them on any computer with the free reader available from www.adobe.com
What we need is a pdf with trim marks and bleed. (See definitions on the right if needed)
It is recommended a minimum 3mm bleed is supplied where any image falls off the edge of a page. Trim marks are also required to cut the printed goods to the correct size. All these settings can be found under the export functions of Indesign and Quark Xpress also the save as commands under Illustrator and Photoshop.
The great thing about creating PDFs is if created correctly it will embed all the fonts used inside it. Otherwise sometimes descrepencies can arise between different profiles on different computers. If using the professional version of Adobe Acrobat be sure to untick the box which says 'do not embed fonts'.