It is very important to make a correct and usable PDF to supply your printer. Before making a PDF, make sure your file is in the correct color mode. Meaning, if you are printing full color, make sure your images and graphics are all CMYK not RGB or Spot color. Make sure your bleeds are all pulled. Spell check and check phone numbers and addresses. Print a color proof and check it. Have someone else proof your job as well. Make sure all your fonts are turned on and all your pictures are either linked or embedded. When making your PDF, make sure to include your Printer Marks and Bleeds. This is very important.