Delete any unused colors from your document

If spot colors are specified, make sure they are not set for process separation

Make sure image files are CMYK and not RGB

Send only necessary files

Make a back-up of your files

If you are sending files on a disk, make sure to include a laser proof (of the latest changes) and make sure your disks are labeled

Print your own laser separations to be sure you get the results you are looking for

Include all linked graphics (EPS, TIFF, etc.)

Label colors identically between documents

Send both screen and printer fonts (Adobe Type 1 preferred) including those that are used in placed images unless they have been changed to outlines

Make sure we have accurate contact info. in case we have questions (it happens, you know)