Run the prepress disk. Preview the document in printer spreads to ensure all pages are laid out correctly, and transfer the design layout to the individual printing plates.
Run make-readys. Make-readys are throwaway passes through a commercial printing press while the ink stations are being cleaned and set, the pressure of the paper is being adjusted, and the press is being cleaned for the run of your job.
Print the printer's proof. The printer's proof is actually for the client's benefit, to ensure any final details that need adjustment are corrected before the job runs.
Note any needed corrections by circling them with a felt-tip marker, and supervise the press operator making the color corrections.
Sign off on the printer's proof, and run the entire printing job.