PDF File Preparation:
Before PDF is created, convert all links to CMYK and make sure they are high resolution (300dpi +).
Also be sure to include 1/8" bleed on any items that extend to the edge of the paper. Be sure to include this dimension in the file size of the PDF file (for example, if the file size is 8.5 x 11 and you have images that bleed off all sides, the PDF size should be 8.75 x 11.25").
All fonts should be embedded or converted to outlines.