Creating a top quality PDF for print is not as straight forward as you might think. It is easy to make a mistake that causes quality problems further down the line.
Fortunately, the Production & Technology committee of the PPA, the Professional Publishers Association, has done a lot of work in this area.
They have issued guidelines for creating PDF’s that are specifically for print.
The single most important tip recommended is to output your PDF as a PDF/X-1a.
This is one of the formats offered in the drop down menu and is ideal as it has been designed specifically for print i.e. it checks for the presence or otherwise of bleed, crop marks, flash, etc.
Have a look at this link. There is a lot of information to get through but I think it is worth it. While most of the information is given in respect to designing for magazines, it has a relevance no matter what sphere you are working in.