Typesetting that appears correct on the computer screen and prints beautifully on your desktop printer will not necessarily output correctly on professional imaging equipment. If you preflight your files you will reduce any possible problems with output and accurate printing.
Printing has complete typesetting and graphic services with hundreds of type faces.
This is by no means a complete tutorial on file preparation, but it will eliminate many of your problems. Save in EPS file format. Scan the line art at 600dpi or higher. Above 1200 dpi is advised. Save in TIFF format.